Fix API hang — switch gaze push from httpx to urllib

httpx.post creates a new connection per call at 10Hz, causing connection
pile-up that eventually blocks the event loop. urllib is lightweight and
stateless — no connection pooling overhead.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

headmic.py

@@ -464,13 +464,16 @@ def doa_track_loop():
 
 
 def _push_gaze(x: int, y: int):
-    """Fire-and-forget gaze push to eye service."""
+    """Fire-and-forget gaze push to eye service. Uses urllib to avoid httpx connection overhead."""
     try:
-        import httpx
+        import urllib.request
-        httpx.post(f"{EYE_SERVICE_URL}/gaze",
+        data = json.dumps({"x": x, "y": y}).encode()
-                   json={"x": x, "y": y}, timeout=0.5)
+        req = urllib.request.Request(
+            f"{EYE_SERVICE_URL}/gaze", data=data,
+            headers={"Content-Type": "application/json"})
+        urllib.request.urlopen(req, timeout=0.3)
     except Exception:
-        pass  # eye service may be down, don't spam logs
+        pass
 
 
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