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/stores/settings-screen.ts

@@ -1,6 +1,6 @@
 import { createSignal } from "solid-js"
 
-export type SettingsSectionId = "appearance" | "notifications" | "remote" | "opencode"
+export type SettingsSectionId = "appearance" | "notifications" | "remote" | "speech" | "opencode"
 
 const [settingsOpen, setSettingsOpen] = createSignal(false)
 const [activeSettingsSection, setActiveSettingsSection] = createSignal<SettingsSectionId>("appearance")