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/components/settings/speech-settings-section.tsx

@@ -0,0 +1,10 @@
+import type { Component } from "solid-js"
+import SpeechSettingsCard from "./speech-settings-card"
+
+export const SpeechSettingsSection: Component = () => {
+  return (
+    <div class="settings-section-stack">
+      <SpeechSettingsCard />
+    </div>
+  )
+}