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/server/src/settings/public-config.ts

@@ -0,0 +1,40 @@
+import type { SettingsDoc } from "./yaml-doc-store"
+
+function isPlainObject(value: unknown): value is Record<string, unknown> {
+  return typeof value === "object" && value !== null && !Array.isArray(value)
+}
+
+function sanitizeServerOwner(value: SettingsDoc): SettingsDoc {
+  const next: SettingsDoc = { ...value }
+  const speech = isPlainObject(next.speech) ? { ...next.speech } : null
+
+  if (!speech) {
+    return next
+  }
+
+  const rawApiKey = typeof speech.apiKey === "string" ? speech.apiKey.trim() : ""
+  if (rawApiKey) {
+    delete speech.apiKey
+    speech.hasApiKey = true
+  } else if (!("hasApiKey" in speech)) {
+    speech.hasApiKey = false
+  }
+
+  next.speech = speech
+  return next
+}
+
+export function sanitizeConfigOwner(owner: string, value: SettingsDoc): SettingsDoc {
+  if (owner !== "server") {
+    return value
+  }
+  return sanitizeServerOwner(value)
+}
+
+export function sanitizeConfigDoc(value: SettingsDoc): SettingsDoc {
+  const next: SettingsDoc = { ...value }
+  if (isPlainObject(next.server)) {
+    next.server = sanitizeServerOwner(next.server)
+  }
+  return next
+}