fix: export/import — отмена пользователем не показывает error toast

Bug: при отмене save-dialog или open-dialog DataCard показывал тост
«Не удалось сохранить» / «Файл не подошёл». Но cancel — это не ошибка.

Расширил IPC возврат: { ok, canceled, path?, error? }. UI теперь
различает: ok → success toast, !ok && canceled → молча, !ok && !canceled
→ error toast.

+9 тестов на validateSettingsPatch для voicePromptsEnabled,
meetingAutoPause, lastSeenVersion (semver-regex / null-сброс /
malformed). Итого 159 → 168 тестов.

Settings → About теперь показывает текущую версию приложения
(раньше была только кнопка «Что нового»). Загружается через
IPC.getAppVersion при mount.

src/main/ipc.ts

@@ -352,12 +352,16 @@ export function registerIpc(): void {
       defaultPath,
       filters: [{ name: 'JSON', extensions: ['json'] }]
     })
-    if (result.canceled || !result.filePath) return { ok: false, path: null }
+    // Cancel — это не ошибка. Возвращаем canceled=true чтобы UI мог
+    // ничего не показывать (без error toast).
+    if (result.canceled || !result.filePath) {
+      return { ok: false, canceled: true, path: null }
+    }
     try {
       writeFileSync(result.filePath, exportState(), 'utf-8')
-      return { ok: true, path: result.filePath }
+      return { ok: true, canceled: false, path: result.filePath }
     } catch (e) {
-      return { ok: false, path: null, error: String(e) }
+      return { ok: false, canceled: false, path: null, error: String(e) }
     }
   })
 
@@ -369,7 +373,7 @@ export function registerIpc(): void {
       filters: [{ name: 'JSON', extensions: ['json'] }]
     })
     if (result.canceled || result.filePaths.length === 0) {
-      return { ok: false }
+      return { ok: false, canceled: true }
     }
     try {
       const raw = readFileSync(result.filePaths[0], 'utf-8')
@@ -378,9 +382,9 @@ export function registerIpc(): void {
         broadcastState()
         broadcastHistoryChanged()
       }
-      return { ok }
+      return { ok, canceled: false }
     } catch (e) {
-      return { ok: false, error: String(e) }
+      return { ok: false, canceled: false, error: String(e) }
     }
   })
 }

src/main/validate.test.ts

@@ -266,6 +266,65 @@ describe('validateSettingsPatch', () => {
     expect(validateSettingsPatch({ snoozeMinutes: -5 })).toBeNull()
   })
 
+  it('accepts voicePromptsEnabled boolean', () => {
+    expect(validateSettingsPatch({ voicePromptsEnabled: true })).toEqual({
+      voicePromptsEnabled: true
+    })
+    expect(validateSettingsPatch({ voicePromptsEnabled: false })).toEqual({
+      voicePromptsEnabled: false
+    })
+  })
+
+  it('rejects non-boolean voicePromptsEnabled in patch', () => {
+    expect(validateSettingsPatch({ voicePromptsEnabled: 'yes' })).toBeNull()
+    expect(validateSettingsPatch({ voicePromptsEnabled: 1 })).toBeNull()
+  })
+
+  it('accepts meetingAutoPause boolean', () => {
+    expect(validateSettingsPatch({ meetingAutoPause: true })).toEqual({
+      meetingAutoPause: true
+    })
+  })
+
+  it('rejects non-boolean meetingAutoPause', () => {
+    expect(validateSettingsPatch({ meetingAutoPause: 'yes' })).toBeNull()
+  })
+
+  describe('lastSeenVersion', () => {
+    it('accepts valid semver', () => {
+      const r = validateSettingsPatch({ lastSeenVersion: '0.5.7' })
+      expect(r?.lastSeenVersion).toBe('0.5.7')
+      expect(validateSettingsPatch({ lastSeenVersion: '10.20.30' })).toEqual({
+        lastSeenVersion: '10.20.30'
+      })
+    })
+
+    it('accepts pre-release suffix', () => {
+      const r = validateSettingsPatch({ lastSeenVersion: '0.5.7-beta.1' })
+      expect(r?.lastSeenVersion).toBe('0.5.7-beta.1')
+    })
+
+    it('treats null/undefined as reset to undefined', () => {
+      const r1 = validateSettingsPatch({ lastSeenVersion: null })
+      expect(r1).toEqual({ lastSeenVersion: undefined })
+      const r2 = validateSettingsPatch({ lastSeenVersion: undefined })
+      // 'lastSeenVersion' is `in raw` even if undefined — both treated reset.
+      expect(r2).toEqual({ lastSeenVersion: undefined })
+    })
+
+    it('rejects malformed strings', () => {
+      expect(validateSettingsPatch({ lastSeenVersion: '0.5' })).toBeNull()
+      expect(validateSettingsPatch({ lastSeenVersion: 'v0.5.7' })).toBeNull()
+      expect(validateSettingsPatch({ lastSeenVersion: 'beta' })).toBeNull()
+      expect(validateSettingsPatch({ lastSeenVersion: '' })).toBeNull()
+    })
+
+    it('rejects non-strings', () => {
+      expect(validateSettingsPatch({ lastSeenVersion: 42 })).toBeNull()
+      expect(validateSettingsPatch({ lastSeenVersion: ['1', '0', '0'] })).toBeNull()
+    })
+  })
+
   describe('quietHours subobject', () => {
     const baseQh = {
       enabled: true,