feat(speech): add prompt voice input (#249)

## Summary
- add server-backed speech capabilities and transcription endpoints plus
UI settings for speech configuration
- add push-to-talk prompt voice input with microphone controls,
transcription insertion, and browser capability gating
- keep prompt controls aligned by restoring right-side nav placement and
moving the mic beside the expand control

packages/ui/src/lib/i18n/messages/en/settings.ts

@@ -65,6 +65,7 @@ export const settingsMessages = {
   "settings.nav.appearance": "Appearance",
   "settings.nav.notifications": "Notifications",
   "settings.nav.remote": "Remote Access",
+  "settings.nav.speech": "Speech",
   "settings.nav.opencode": "OpenCode",
   "settings.scope.device": "This device",
   "settings.scope.server": "Server setting",
@@ -137,6 +138,38 @@ export const settingsMessages = {
   "settings.behavior.usageMetrics.subtitle": "Show or hide token and cost stats for assistant messages.",
   "settings.behavior.autoCleanup.title": "Auto-cleanup blank sessions",
   "settings.behavior.autoCleanup.subtitle": "Automatically clean up blank sessions when creating new ones.",
+  "settings.behavior.promptVoiceInput.title": "Prompt voice input",
+  "settings.behavior.promptVoiceInput.subtitle": "Show the microphone control for speech-to-text prompt input when speech is configured.",
   "settings.behavior.promptSubmit.title": "Enter to submit",
   "settings.behavior.promptSubmit.subtitle": "Use Enter to submit prompts; Cmd/Ctrl+Enter inserts a new line.",
+  "settings.speech.title": "Speech",
+  "settings.speech.subtitle": "Configure speech-to-text now and text-to-speech groundwork for later features.",
+  "settings.speech.provider.title": "Provider",
+  "settings.speech.provider.subtitle": "Speech requests use the server-side speech adapter.",
+  "settings.speech.provider.openaiCompatible": "OpenAI-compatible",
+  "settings.speech.status.loading": "Checking configuration...",
+  "settings.speech.status.configured": "Configured",
+  "settings.speech.status.missing": "Missing API key",
+  "settings.speech.status.error": "Speech service unavailable",
+  "settings.speech.apiKey.title": "API key",
+  "settings.speech.apiKey.subtitle": "Used for CodeNomad-managed speech requests.",
+  "settings.speech.apiKey.placeholder": "Enter a new API key",
+  "settings.speech.apiKey.storedNote": "A saved API key is hidden. Enter a new value to replace it, or leave the field blank to keep it.",
+  "settings.speech.apiKey.clearAction": "Clear saved key",
+  "settings.speech.apiKey.clearPending": "The saved API key will be removed when you save.",
+  "settings.speech.baseUrl.title": "Base URL",
+  "settings.speech.baseUrl.subtitle": "Optional override for OpenAI-compatible speech endpoints.",
+  "settings.speech.baseUrl.placeholder": "https://api.openai.com/v1",
+  "settings.speech.sttModel.title": "Transcription model",
+  "settings.speech.sttModel.subtitle": "Model used for prompt speech-to-text requests.",
+  "settings.speech.ttsModel.title": "Speech model",
+  "settings.speech.ttsModel.subtitle": "Default text-to-speech model reserved for future playback features.",
+  "settings.speech.ttsVoice.title": "Default voice",
+  "settings.speech.ttsVoice.subtitle": "Default text-to-speech voice reserved for future playback features.",
+  "settings.speech.help": "Prompt voice input only appears when speech transcription is configured and supported by this browser.",
+  "settings.speech.save.action": "Save",
+  "settings.speech.save.saving": "Saving...",
+  "settings.speech.save.saved": "Saved",
+  "settings.speech.save.unsaved": "Unsaved changes",
+  "settings.speech.save.error": "Save failed",
 } as const