Bump to v2.3.0: replace polling with SSE stream, fix detector imports

- Add GET /stream SSE endpoint to aggregator.py; state is pushed
  instantly on every change instead of fetched every 2s
- Replace setInterval polling in index.html with EventSource;
  onerror shows the ( ?.?) face and auto-reconnect is handled by
  the browser natively
- Fix ModuleNotFoundError in detectors: inject project root into
  PYTHONPATH when launching subprocesses from kao.py
- Update openapi.yaml, CLAUDE.md, README.md with /stream endpoint
- Remove completed SSE item from TODO.md

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

aggregator.py

@@ -5,12 +5,13 @@ A lightweight event broker that manages priority-based system status.
 
 import json
 import os
+import queue
 import random
 import threading
 import time
 from datetime import datetime
 from pathlib import Path
-from flask import Flask, request, jsonify, send_from_directory
+from flask import Flask, request, jsonify, send_from_directory, Response, stream_with_context
 
 app = Flask(__name__, static_folder=".")
 ROOT_DIR = Path(__file__).parent
@@ -60,6 +61,23 @@ current_optimal_animation = OPTIMAL_EMOTES[0][1]
 # Notify counter for unique IDs
 _notify_counter = 0
 
+# SSE subscribers: one queue per connected client
+_subscribers: set = set()
+_subscribers_lock = threading.Lock()
+
+
+def broadcast(state_json: str):
+    """Push state JSON to all connected SSE clients."""
+    with _subscribers_lock:
+        dead = []
+        for q in _subscribers:
+            try:
+                q.put_nowait(state_json)
+            except queue.Full:
+                dead.append(q)
+        for q in dead:
+            _subscribers.discard(q)
+
 # Sleep mode
 is_sleeping = False
 SLEEP_EMOTE = "( -_-)zzZ"
@@ -156,13 +174,14 @@ def get_current_state():
 
 
 def write_status():
-    """Write current state to status.json."""
+    """Write current state to status.json and push to SSE subscribers."""
     state = get_current_state()
     try:
         with open(STATUS_FILE, "w") as f:
             json.dump(state, f, indent="\t")
     except OSError as e:
         print(f"[ERROR] Failed to write status file: {e}")
+    broadcast(json.dumps(state))
     return state
 
 
@@ -351,6 +370,38 @@ def list_events():
         return jsonify({"events": dict(active_events)}), 200
 
 
+@app.route("/stream")
+def stream():
+    """Server-Sent Events stream. Pushes state JSON on every change."""
+    q = queue.Queue(maxsize=10)
+    with _subscribers_lock:
+        _subscribers.add(q)
+
+    def generate():
+        try:
+            # Send current state immediately on connect
+            yield f"data: {json.dumps(get_current_state())}\n\n"
+            while True:
+                try:
+                    data = q.get(timeout=30)
+                    yield f"data: {data}\n\n"
+                except queue.Empty:
+                    # Keepalive comment to prevent proxy timeouts
+                    yield ": keepalive\n\n"
+        finally:
+            with _subscribers_lock:
+                _subscribers.discard(q)
+
+    return Response(
+        stream_with_context(generate()),
+        mimetype="text/event-stream",
+        headers={
+            "Cache-Control": "no-cache",
+            "X-Accel-Buffering": "no",  # Disable nginx buffering if proxied
+        },
+    )
+
+
 @app.route("/docs")
 def docs():
     """Serve interactive API documentation via Swagger UI."""