feat: integrate Tauri v2 with Android widget and voice assistant

- Add Tauri v2 shell (Cargo, tauri.conf.json, capabilities, plugins)
- Migrate all fetch() calls to apiFetch() for Tauri-aware HTTP
- Migrate WebSocket endpoints to resolveEndpoints() for dynamic URLs
- Add ServerConfigDialog for remote server URL configuration
- Add tauri.ts lib with isTauri detection, apiFetch wrapper, plugin helpers
- Add server-config Pinia store with persistence via plugin-store
- Conditional PWA (disabled in Tauri builds)
- Android: home screen transcript widget (last 5 messages, 30s refresh)
- Android: voice command / share activity (SpeechRecognizer + WebSocket)
- Android: signed release APK with auto-copy to installers/
- Remove stale frontend/src-tauri directory

frontend/src/components/transcript-debug/NewSessionModal.vue

@@ -1,5 +1,6 @@
 <script setup lang="ts">
 import { ref, computed, watch } from 'vue'
+import { apiFetch } from '@/lib/tauri'
 import type { AgentName, SessionInfo } from '@/types/transcript-debug'
 
 const props = defineProps<{
@@ -51,7 +52,7 @@ async function fetchAllSessions() {
   await Promise.all(
     props.agents.map(async (a) => {
       try {
-        const res = await fetch(`/api/transcript-debug/sessions?agent=${a.id}`)
+        const res = await apiFetch(`/api/transcript-debug/sessions?agent=${a.id}`)
         if (res.ok) map[a.id] = await res.json()
         else map[a.id] = []
       } catch {