feat: expand secure assistant workflows

Harden runtime execution and add local knowledge, Smart Heartbeat, usage visibility, responsive product surfaces, and cross-platform packaging support.

Co-authored-by: factory-droid[bot] <138933559+factory-droid[bot]@users.noreply.github.com>

src/main/assistant/heartbeat-recurrence.test.ts

@@ -0,0 +1,41 @@
+import { describe, expect, it } from 'vitest'
+import {
+  assertValidHeartbeatTimezone,
+  computeNextHeartbeatRun
+} from './heartbeat-recurrence'
+
+describe('heartbeat recurrence', () => {
+  it('keeps daily wall-clock time across daylight-saving changes', () => {
+    expect(
+      computeNextHeartbeatRun(
+        { type: 'daily', localTime: '02:30' },
+        'America/New_York',
+        new Date('2026-03-07T12:00:00.000Z')
+      ).toISOString()
+    ).toBe('2026-03-08T07:00:00.000Z')
+
+    expect(
+      computeNextHeartbeatRun(
+        { type: 'daily', localTime: '01:30' },
+        'America/New_York',
+        new Date('2026-11-01T05:31:00.000Z')
+      ).toISOString()
+    ).toBe('2026-11-01T06:30:00.000Z')
+  })
+
+  it('computes weekly recurrence using the configured local weekday', () => {
+    expect(
+      computeNextHeartbeatRun(
+        { type: 'weekly', weekday: 1, localTime: '09:15' },
+        'Asia/Tokyo',
+        new Date('2026-07-31T00:00:00.000Z')
+      ).toISOString()
+    ).toBe('2026-08-03T00:15:00.000Z')
+  })
+
+  it('rejects invalid IANA timezones', () => {
+    expect(() =>
+      assertValidHeartbeatTimezone('Not/A_Timezone')
+    ).toThrow('Invalid heartbeat timezone')
+  })
+})