fix: voice input in Electron - local Whisper STT + network error handling

- Add local Whisper STT via Transformers.js with Web Worker (no UI freeze)
- Default sttProvider to 'local' in Electron (browser STT unavailable)
- Fix infinite toast loop: stop auto-restart on network errors
- Add retry limit with exponential backoff for transient STT errors
- Append voice transcript to input field (append-inline), not replace
- Add model catalog with download/load button in Voice Settings

packages/web/server/lib/opencode/settings-helpers.js

@@ -604,7 +604,7 @@ export const createSettingsHelpers = (dependencies) => {
 
     if (typeof candidate.sttProvider === 'string') {
       const provider = candidate.sttProvider.trim();
-      if (provider === 'browser' || provider === 'server') {
+      if (provider === 'browser' || provider === 'server' || provider === 'wasm') {
         result.sttProvider = provider;
       }
     }
@@ -620,6 +620,12 @@ export const createSettingsHelpers = (dependencies) => {
         result.sttModel = trimmed;
       }
     }
+    if (typeof candidate.wasmSttModel === 'string') {
+      const trimmed = candidate.wasmSttModel.trim();
+      if (trimmed.length <= 256) {
+        result.wasmSttModel = trimmed;
+      }
+    }
     if (typeof candidate.sttLanguage === 'string') {
       const trimmed = candidate.sttLanguage.trim();
       if (trimmed.length <= STT_LANGUAGE_MAX_LENGTH) {