feat(voice): first-class voice input and local TTS across web, desktop, and mobile (#2018)

Complete rebuild of voice input on a server-authoritative streaming
architecture, replacing the legacy Web Speech / whole-blob / WASM engines
and the dead voice-agent layer (~4k lines removed).

Speech-to-text (dictation):
- Client streams 16 kHz mono PCM16 chunks over /api/dictation/ws with
  seq/ack ordering; buffered audio is retained and replayed on reconnect
- Server transcribes and streams live partial transcripts back;
  segments auto-commit every ~15s with silence suppression and adaptive
  finalization timeouts
- Local provider (default, zero config): sherpa-onnx models in a forked
  worker process — auto-download with progress, staged extraction with
  verification, corrupt-model auto-recovery, idle shutdown after 5 min
- Model catalog with settings picker (accuracy/speed ratings, sizes,
  download/delete): Parakeet TDT v2 (English) and v3 (25 European
  languages, auto-detected), Whisper base and tiny (multilingual, light)
- OpenAI-compatible provider for any Whisper endpoint
- Composer overlay with live transcript, volume meter, timer, and
  cancel / insert / insert-and-send actions; failed transcriptions keep
  their audio for retry or accepting the partial text as-is
- Configurable keyboard shortcut (default mod+alt+v) toggles dictation;
  Enter confirms and Escape cancels while recording
- Overlay is pixel-aligned with the composer (measured footer height,
  matching paddings/typography/gaps) — no layout shift when toggling

Text-to-speech:
- Local Kokoro provider (English, 11 voices) synthesized in the same
  worker via /api/dictation/tts/speak, managed by the shared model
  pipeline; sentence-pipelined playback keeps time-to-first-audio at
  ~1 sentence regardless of message length, and stop cancels in-flight
  synthesis
- Sanitizer keeps inline-code content (strips backticks only), reads
  interword slashes aloud, and removes only absolute file paths

Settings:
- Voice page unified: a single read-aloud toggle owns all playback
  options (the confusing "Enable Voice Mode" is gone); a new "Enable
  voice input" toggle (default on, persisted to settings.json) hides
  the composer mic entirely when disabled

Mobile and transport:
- iOS/Android microphone permissions added (dictation was previously
  impossible on mobile)
- Fixed Android WebSocket upgrades: the Capacitor WebView origin
  (https://localhost) was missing from the packaged-client allowlist,
  403-ing every WS connection — root cause of the old mobile SSE lock,
  which is now removed for all transports

Security and conventions:
- All HTTP routes sit behind the global /api auth gate; the WS upgrade
  explicitly validates the UI session and origin, with oc_url_token
  narrowly allowlisted and covered by tests; the dictation socket mints
  a fresh URL token before connecting
- Routes register before the generic OpenCode proxy; the client goes
  through runtimeFetch/getRuntimeUrlResolver, and runtime switches
  reset the dictation socket
- VS Code deliberately reports dictation as unavailable (no server
  process in that runtime)

CI: workflow Node bumped 20 -> 22 to match the repo engines and fix
better-sqlite3 installs broken by node-gyp@latest on Node 20.

New dependency: sherpa-onnx-node (prebuilt N-API; macOS/Linux x64+arm64,
Windows x64 — Windows-on-ARM falls back to the OpenAI-compatible provider)

packages/ui/src/hooks/useMessageTTS.ts

@@ -9,6 +9,7 @@ import { useCallback, useState } from 'react';
 import { useConfigStore } from '@/stores/useConfigStore';
 import { useServerTTS } from './useServerTTS';
 import { useSayTTS } from './useSayTTS';
+import { useLocalTTS } from './useLocalTTS';
 import { browserVoiceService } from '@/lib/voice/browserVoiceService';
 import { sanitizeForTTS } from '@/lib/voice/summarize';
 
@@ -29,6 +30,7 @@ export function useMessageTTS(): UseMessageTTSReturn {
     const speechPitch = useConfigStore((state) => state.speechPitch);
     const speechVolume = useConfigStore((state) => state.speechVolume);
     const sayVoice = useConfigStore((state) => state.sayVoice);
+    const localTtsVoiceId = useConfigStore((state) => state.localTtsVoiceId);
     const browserVoice = useConfigStore((state) => state.browserVoice);
     const openaiVoice = useConfigStore((state) => state.openaiVoice);
     const openaiCompatibleVoice = useConfigStore((state) => state.openaiCompatibleVoice);
@@ -48,13 +50,15 @@ export function useMessageTTS(): UseMessageTTSReturn {
     const { speak: speakSayTTS, stop: stopSayTTS, isAvailable: isSayTTSAvailable } = useSayTTS({
         enabled: shouldCheckSayAvailability,
     });
+    const { speak: speakLocalTTS, stop: stopLocalTTS } = useLocalTTS();
     
     const stop = useCallback(() => {
         setIsPlaying(false);
         stopServerTTS();
         stopSayTTS();
+        stopLocalTTS();
         browserVoiceService.cancelSpeech();
-    }, [stopServerTTS, stopSayTTS]);
+    }, [stopServerTTS, stopSayTTS, stopLocalTTS]);
     
     const play = useCallback(async (text: string) => {
         if (!text.trim()) return;
@@ -84,6 +88,13 @@ export function useMessageTTS(): UseMessageTTSReturn {
                     onEnd: () => setIsPlaying(false),
                     onError: () => setIsPlaying(false),
                 });
+            } else if (voiceProvider === 'local') {
+                await speakLocalTTS(sanitizedText, {
+                    speakerId: localTtsVoiceId,
+                    speed: speechRate,
+                    onEnd: () => setIsPlaying(false),
+                    onError: () => setIsPlaying(false),
+                });
             } else if (voiceProvider === 'say' && isSayTTSAvailable) {
                 const wordsPerMinute = Math.round(100 + (speechRate - 0.5) * 200);
                 await speakSayTTS(sanitizedText, {
@@ -129,6 +140,8 @@ export function useMessageTTS(): UseMessageTTSReturn {
         ttsInputMode,
         speakServerTTS,
         speakSayTTS,
+        speakLocalTTS,
+        localTtsVoiceId,
         stop,
     ]);