feat(proxy-engine): integrate Kokoro TTS generation into proxy-engine and simplify TypeScript prompt handling to use cached WAV files

ts/proxybridge.ts

@@ -79,6 +79,10 @@ type TProxyCommands = {
     params: { call_id: string; leg_id: string; key: string; value: unknown };
     result: Record<string, never>;
   };
+  generate_tts: {
+    params: { model: string; voices: string; voice: string; text: string; output: string };
+    result: { output: string };
+  };
 };
 
 // ---------------------------------------------------------------------------
@@ -493,6 +497,15 @@ export function isProxyReady(): boolean {
   return initialized && bridge !== null;
 }
 
+/** Send an arbitrary command to the proxy engine bridge. */
+export async function sendProxyCommand<K extends keyof TProxyCommands>(
+  method: K,
+  params: TProxyCommands[K]['params'],
+): Promise<TProxyCommands[K]['result']> {
+  if (!bridge || !initialized) throw new Error('proxy engine not initialized');
+  return bridge.sendCommand(method as string, params as any) as any;
+}
+
 /** Shut down the proxy engine. */
 export function shutdownProxyEngine(): void {
   if (bridge) {