feat(tower): add gateway TTS helper

Add tts_speak() function to call the tailnet gateway TTS endpoint
(model tts-1, voice fr, response mp3). Configurable via LISAEL_TTS_URL
and LISAEL_TTS_VOICE env vars. Returns raw mp3 bytes, raises on failure.

tower/lisael_content.py

@@ -12,6 +12,8 @@ LVGLIMG    = os.environ.get("LISAEL_LVGLIMG", os.path.join(BASE, "LVGLImage.py")
 FEEDS_JSON = os.path.join(BASE, "feeds.json")
 BOX_JSON   = os.path.join(BASE, "box-state.json")
 BOX_PORT   = int(os.environ.get("LISAEL_BOX_PORT", "8080"))
+TTS_URL    = os.environ.get("LISAEL_TTS_URL", "http://100.78.6.122:9300/v1/audio/speech")
+TTS_VOICE  = os.environ.get("LISAEL_TTS_VOICE", "fr")
 UA  = {"User-Agent": "Mozilla/5.0"}
 NS  = {"itunes": "http://www.itunes.com/dtds/podcast-1.0.dtd"}
 SUBS = {"’": "'", "“": '"', "”": '"', "–": "-",
@@ -104,6 +106,16 @@ def transcode(raw_path, out_path):
                         capture_output=True).returncode
     return rc == 0 and os.path.exists(out_path)
 
+def tts_speak(text):
+    """Generate a mono mp3 announcement via the tailnet gateway. Returns bytes.
+    Raises on network/HTTP failure (caller decides degraded behaviour)."""
+    body = json.dumps({"model": "tts-1", "input": text, "voice": TTS_VOICE,
+                       "response_format": "mp3"}).encode()
+    req = urllib.request.Request(TTS_URL, data=body,
+                                 headers={"Content-Type": "application/json"})
+    with urllib.request.urlopen(req, timeout=30) as r:
+        return r.read()
+
 def make_cover(img_bytes, key):
     """160x160 RGB565 .bin into STAGING via LVGLImage. Returns '<key>.bin' or ''."""
     try: