feat: a11y + Error Boundary + IPC validation + schema migrations

Second pass through the audit punch-list. ESLint and Prettier now clean
(0 errors, 0 warnings), typecheck clean, 53 tests pass.

ACCESSIBILITY (Modal)
- Full focus trap: Tab/Shift-Tab cycle within the dialog and never
  escape to the underlying page.
- Focus restoration: closing returns focus to the trigger button.
- First focusable child is focused on open (skipping the X button).
- aria-labelledby links the dialog to its <h2> via useId().
- Close button's hardcoded "Закрыть" replaced with i18n key.

ERROR RECOVERY
- Add ErrorBoundary component (class — only way) with localized
  fallback and a "try again" reset button. Stack trace shown only in
  dev. Wrapped around the whole App + a nested boundary around the
  routed pages so a crash in one route doesn't blank the chrome.
- Module-level guard on subscribeToBackend so React 18 StrictMode's
  dev-mode double-mount doesn't subscribe twice.
- Loading placeholder is now blank (was hardcoded Russian "Загрузка…"
  that English users would see during initial hydration).

TRAY i18n
- 5 tray strings now follow the current settings.language. Falls back
  to Russian when the store isn't loaded yet or the lang is unknown.
- refreshMenu() called on settings.language change and on
  pauseAll/resumeAll so the pause label stays in sync with state.

IPC VALIDATION (src/main/validate.ts)
- Hand-rolled validators for every renderer-supplied payload:
  exercise input/patch, challenge input/patch, settings patch, id,
  actualReps, snoozeMinutes. Range-check numeric fields
  (intervalMinutes ∈ [1, 1440], reps ∈ [1, 9999], multiplier ∈ [0,
  1000], snooze ∈ [1, 1440]), cap string lengths at 200, restrict
  enums (theme/lang/notify-mode/stat) to known values, validate
  quietHours.from/to with HH:MM regex and dedup quietHours.days.
- Every ipcMain.handle for mutations now runs the validator first and
  returns null on rejection instead of pushing junk into the store.
  A compromised renderer can no longer corrupt persisted state via
  out-of-range numbers or wrong-type fields.

SCHEMA MIGRATIONS (src/main/store.ts)
- Add __schemaVersion field to persisted state with CURRENT = 1.
- MIGRATIONS map: { 0: (s) => s } as a no-op seed; future structural
  changes (e.g. quietHours shape revision) get a single explicit slot.
- runMigrations() applies migrations in order; coerce() normalises the
  result into a fully-formed AppState. Both first-write and every
  flush() persist the version field.

EXHAUSTIVE-DEPS WARNINGS
- Dashboard: memoise `exercises` so downstream useMemos don't fire on
  every parent render; gate the history fetch on exercises change
  instead of any state change.
- HistoryHeatmap: wrap `weeks` in useMemo so monthLabels' deps are
  stable.

LINT POLISH
- updater.ts: refactor a Prettier-vs-no-extra-semi conflict by
  extracting the cast into a local binding.
- Remove dead import of `Challenge` from ipc.ts (now imported via
  validators).

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/main/ipc.ts

@@ -7,7 +7,7 @@ import {
   shell
 } from 'electron'
 import { IPC } from '@shared/ipc'
-import type { Challenge, Exercise, GameId, Settings } from '@shared/types'
+import type { Exercise, GameId, Settings } from '@shared/types'
 import {
   addChallenge,
   addExercise,
@@ -28,6 +28,7 @@ import { broadcastState } from './state-actions'
 import { setAutostart, isAutostartEnabled } from './autostart'
 import { setPaused, forceCheck } from './scheduler'
 import { hideReminderWindow, getMainWindow } from './windows'
+import { refreshMenu } from './tray'
 import {
   broadcastGames,
   installGame,
@@ -42,6 +43,16 @@ import {
   getUpdaterStatus,
   quitAndInstall
 } from './updater'
+import {
+  validateActualReps,
+  validateChallengeInput,
+  validateChallengePatch,
+  validateExerciseInput,
+  validateExercisePatch,
+  validateId,
+  validateSettingsPatch,
+  validateSnoozeMinutes
+} from './validate'
 
 export function registerIpc(): void {
   ipcMain.handle(IPC.getState, () => {
@@ -50,60 +61,78 @@ export function registerIpc(): void {
     return state
   })
 
-  ipcMain.handle(
-    IPC.addExercise,
-    (_e, input: Omit<Exercise, 'id' | 'nextFireAt' | 'lastDoneAt'>) => {
-      const ex = addExercise(input)
-      broadcastState()
-      return ex
-    }
-  )
+  ipcMain.handle(IPC.addExercise, (_e, input: unknown) => {
+    const safe = validateExerciseInput(input)
+    if (!safe) return null
+    const ex = addExercise(safe)
+    broadcastState()
+    return ex
+  })
 
   ipcMain.handle(
     IPC.updateExercise,
-    (_e, id: string, patch: Partial<Exercise>) => {
+    (_e, idRaw: unknown, patchRaw: unknown) => {
+      const id = validateId(idRaw)
+      const patch = validateExercisePatch(patchRaw)
+      if (!id || !patch) return null
       const ex = updateExercise(id, patch)
       broadcastState()
       return ex
     }
   )
 
-  ipcMain.handle(IPC.deleteExercise, (_e, id: string) => {
+  ipcMain.handle(IPC.deleteExercise, (_e, idRaw: unknown) => {
+    const id = validateId(idRaw)
+    if (!id) return false
     const ok = deleteExercise(id)
     broadcastState()
     return ok
   })
 
-  ipcMain.handle(IPC.toggleExercise, (_e, id: string, enabled: boolean) => {
-    const patch: Partial<Exercise> = { enabled }
-    if (enabled) {
-      const ex = getState().exercises.find((e) => e.id === id)
-      if (ex) patch.nextFireAt = Date.now() + ex.intervalMinutes * 60_000
+  ipcMain.handle(
+    IPC.toggleExercise,
+    (_e, idRaw: unknown, enabledRaw: unknown) => {
+      const id = validateId(idRaw)
+      if (!id || typeof enabledRaw !== 'boolean') return null
+      const patch: Partial<Exercise> = { enabled: enabledRaw }
+      if (enabledRaw) {
+        const ex = getState().exercises.find((e) => e.id === id)
+        if (ex) patch.nextFireAt = Date.now() + ex.intervalMinutes * 60_000
+      }
+      const ex = updateExercise(id, patch)
+      broadcastState()
+      return ex
     }
-    const ex = updateExercise(id, patch)
+  )
+
+  ipcMain.handle(IPC.markDone, (_e, idRaw: unknown, repsRaw?: unknown) => {
+    const id = validateId(idRaw)
+    if (!id) return null
+    const ex = markDone(id, validateActualReps(repsRaw))
     broadcastState()
     return ex
   })
 
-  ipcMain.handle(IPC.markDone, (_e, id: string, actualReps?: number) => {
-    const ex = markDone(id, actualReps)
-    broadcastState()
-    return ex
-  })
-
-  ipcMain.handle(IPC.snooze, (_e, id: string, minutes: number) => {
+  ipcMain.handle(IPC.snooze, (_e, idRaw: unknown, minRaw: unknown) => {
+    const id = validateId(idRaw)
+    const minutes = validateSnoozeMinutes(minRaw)
+    if (!id || minutes === null) return null
     const ex = snooze(id, minutes)
     broadcastState()
     return ex
   })
 
-  ipcMain.handle(IPC.skip, (_e, id: string) => {
+  ipcMain.handle(IPC.skip, (_e, idRaw: unknown) => {
+    const id = validateId(idRaw)
+    if (!id) return null
     const ex = skip(id)
     broadcastState()
     return ex
   })
 
-  ipcMain.handle(IPC.updateSettings, (_e, patch: Partial<Settings>) => {
+  ipcMain.handle(IPC.updateSettings, (_e, patchRaw: unknown) => {
+    const patch = validateSettingsPatch(patchRaw)
+    if (!patch) return null
     if (patch.startWithWindows !== undefined) {
       setAutostart(patch.startWithWindows)
     }
@@ -113,9 +142,21 @@ export function registerIpc(): void {
     }
     const settings = updateSettings(merged)
     broadcastState()
+    // Language change reflects in the tray menu next time it's opened.
+    if (patch.language !== undefined) refreshMenu()
     return settings
   })
 
+  ipcMain.handle(IPC.pauseAll, () => {
+    setPaused(true)
+    refreshMenu()
+  })
+  ipcMain.handle(IPC.resumeAll, () => {
+    setPaused(false)
+    forceCheck()
+    refreshMenu()
+  })
+
   ipcMain.handle(IPC.getAccentColor, () => {
     try {
       return '#' + systemPreferences.getAccentColor()
@@ -128,12 +169,6 @@ export function registerIpc(): void {
     nativeTheme.shouldUseDarkColors ? 'dark' : 'light'
   )
 
-  ipcMain.handle(IPC.pauseAll, () => setPaused(true))
-  ipcMain.handle(IPC.resumeAll, () => {
-    setPaused(false)
-    forceCheck()
-  })
-
   ipcMain.handle(IPC.quit, () => app.quit())
   ipcMain.handle(IPC.reminderClose, () => hideReminderWindow())
 
@@ -186,29 +221,41 @@ export function registerIpc(): void {
   })
 
   // Challenges
-  ipcMain.handle(IPC.addChallenge, (_e, input: Omit<Challenge, 'id'>) => {
-    const c = addChallenge(input)
+  ipcMain.handle(IPC.addChallenge, (_e, input: unknown) => {
+    const safe = validateChallengeInput(input)
+    if (!safe) return null
+    const c = addChallenge(safe)
     broadcastState()
     return c
   })
   ipcMain.handle(
     IPC.updateChallenge,
-    (_e, id: string, patch: Partial<Challenge>) => {
+    (_e, idRaw: unknown, patchRaw: unknown) => {
+      const id = validateId(idRaw)
+      const patch = validateChallengePatch(patchRaw)
+      if (!id || !patch) return null
       const c = updateChallenge(id, patch)
       broadcastState()
       return c
     }
   )
-  ipcMain.handle(IPC.deleteChallenge, (_e, id: string) => {
+  ipcMain.handle(IPC.deleteChallenge, (_e, idRaw: unknown) => {
+    const id = validateId(idRaw)
+    if (!id) return false
     const ok = deleteChallenge(id)
     broadcastState()
     return ok
   })
-  ipcMain.handle(IPC.toggleChallenge, (_e, id: string, enabled: boolean) => {
-    const c = updateChallenge(id, { enabled })
-    broadcastState()
-    return c
-  })
+  ipcMain.handle(
+    IPC.toggleChallenge,
+    (_e, idRaw: unknown, enabledRaw: unknown) => {
+      const id = validateId(idRaw)
+      if (!id || typeof enabledRaw !== 'boolean') return null
+      const c = updateChallenge(id, { enabled: enabledRaw })
+      broadcastState()
+      return c
+    }
+  )
 
   ipcMain.handle(IPC.closeMatchSummary, () => hideReminderWindow())