Add README, faster-whisper backend, and session fixes

- README explaining experimental/transparency purpose
- faster-whisper STT backend (fw-stt.mjs, faster-whisper-server.py, install-faster-whisper.sh)
- Bug fixes: Buffer alignment in on_audio, --debug-waveform URL parsing, silent fetch errors, instant dispatch timer leak
- Global uncaughtException/unhandledRejection handlers in query-demo.mjs
- Design docs: CHANGELOG, COMMAND-DISPATCH, INTERFACE-THEORY, VOICE-POLICY
- Systemd service unit templates

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

tts-server.mjs

@@ -153,11 +153,19 @@ const server = http.createServer(async (req, res) => {
 			opts.audio_prompt = voices[current_voice].path
 		}
 
-		try {
-			await enqueue(() => tts.speak_streaming(text, { preprocess: false, ...opts }))
-			send(res, 200, { ok: true })
-		} catch (err) {
-			send(res, 500, { error: err.message })
+		const wait = opts.wait === true
+		const promise = enqueue(() => tts.speak_streaming(text, { preprocess: false, ...opts }))
+
+		if (wait) {
+			try {
+				await promise
+				send(res, 200, { ok: true })
+			} catch (err) {
+				send(res, 500, { error: err.message })
+			}
+		} else {
+			promise.catch(err => console.error('speak error:', err.message))
+			send(res, 200, { ok: true, queued: true })
 		}
 		return
 	}