Add complete REST API for lighting control

- Migrated from websockets to aiohttp for unified HTTP/WebSocket server
- Added REST endpoints: /api/pattern, /api/parameters, /api/state, /api/tempo/reset
- Implemented color palette API with 8-slot system and selected colors
- First selected color (index 0) is used as primary RGB for patterns
- All operations now available via simple HTTP requests (no WebSocket needed)
- Added comprehensive documentation: FRONTEND_API.md, COLOR_PALETTE_API.md
- Added test scripts: test_rest_api.sh, test_color_patterns.py
- Updated test/test_control_server.py for new /ws WebSocket path
- Configuration persistence via lighting_config.json
- Pattern parameters (n1-n4, brightness, delay) controllable via API
- WebSocket still available at /ws for legacy support

AIOHTTP_MIGRATION.md

@@ -0,0 +1,148 @@
+# Migration to aiohttp for WebSocket and HTTP
+
+## Summary
+
+The control server has been refactored to use **aiohttp** for both WebSocket and HTTP endpoints, replacing the previous `websockets` library for the WebSocket server.
+
+## What Changed
+
+### 1. Server Architecture
+
+**Before:**
+- Separate `websockets` server on port 8765
+- Separate `aiohttp` HTTP API server on port 8766
+
+**After:**
+- Single `aiohttp` application serving both:
+  - WebSocket endpoint: `ws://host:8765/ws`
+  - HTTP API endpoints: `http://host:8765/api/*`
+  - HTTP API also available on port 8766 for backward compatibility
+
+### 2. Code Changes
+
+#### `/home/pi/lighting-controller/src/control_server.py`
+
+**Removed:**
+- `import websockets`
+- `handle_ui_client()` method (used websockets library)
+- `start_websocket_server()` method
+- `_websocket_server_task()` method
+
+**Added:**
+- `handle_websocket()` method using aiohttp's WebSocket support
+- Updated `start_http_server()` to include WebSocket endpoint
+- Combined server startup (HTTP and WebSocket on same port)
+
+**Key Differences:**
+
+```python
+# OLD (websockets library)
+async def handle_ui_client(self, websocket):
+    async for message in websocket:
+        data = json.loads(message)
+        await websocket.send(json.dumps(response))
+
+# NEW (aiohttp)
+async def handle_websocket(self, request):
+    ws = web.WebSocketResponse()
+    await ws.prepare(request)
+    async for msg in ws:
+        if msg.type == web.WSMsgType.TEXT:
+            data = json.loads(msg.data)
+            await ws.send_json(response)
+    return ws
+```
+
+#### `/home/pi/lighting-controller/Pipfile`
+
+Both `aiohttp` and `websockets` are now in the dependencies:
+- `aiohttp` - for server WebSocket and HTTP
+- `websockets` - for client connections to LED bars (in `networking.py`)
+
+### 3. Client Changes Required
+
+**WebSocket URL Update:**
+
+Clients must update their connection URL to include the `/ws` path:
+
+```javascript
+// OLD
+const ws = new WebSocket('ws://10.42.0.1:8765');
+
+// NEW
+const ws = new WebSocket('ws://10.42.0.1:8765/ws');
+```
+
+**Python Client:**
+```python
+# OLD
+uri = "ws://10.42.0.1:8765"
+
+# NEW
+uri = "ws://10.42.0.1:8765/ws"
+```
+
+### 4. HTTP API
+
+The HTTP API endpoints remain the same, but are now available on both ports:
+
+- **Primary:** `http://10.42.0.1:8765/api/color-palette`
+- **Backward Compatibility:** `http://10.42.0.1:8766/api/color-palette`
+
+### 5. Configuration
+
+Environment variables remain the same:
+
+```bash
+CONTROL_SERVER_HOST=0.0.0.0
+CONTROL_SERVER_PORT=8765
+HTTP_API_PORT=8766
+```
+
+## Benefits
+
+1. **Unified Server:** Single aiohttp application handles all HTTP and WebSocket traffic
+2. **Easier CORS:** Can add CORS middleware once for both REST and WebSocket
+3. **Simpler Deployment:** One port for UI clients (WebSocket + API)
+4. **Standard REST Patterns:** aiohttp's routing and middleware ecosystem
+5. **Less Dependencies:** One web framework instead of two
+
+## Testing
+
+### Test WebSocket Connection
+
+```bash
+# Python test client
+pipenv run python test/test_control_server.py --pattern rainbow
+```
+
+### Test HTTP API
+
+```bash
+# Get color palette
+curl http://localhost:8765/api/color-palette
+
+# Update selected colors
+curl -X POST http://localhost:8765/api/color-palette \
+  -H "Content-Type: application/json" \
+  -d '{"selected_indices": [3, 6]}'
+```
+
+## Backward Compatibility
+
+- HTTP API still available on port 8766
+- WebSocket protocol unchanged (JSON message format)
+- Only the WebSocket URL path changed (added `/ws`)
+
+## Files Modified
+
+1. `/home/pi/lighting-controller/src/control_server.py` - Main refactor
+2. `/home/pi/lighting-controller/Pipfile` - Dependencies (kept both aiohttp and websockets)
+3. `/home/pi/lighting-controller/COLOR_PALETTE_API.md` - Updated documentation
+
+## Files NOT Modified
+
+- `/home/pi/lighting-controller/src/networking.py` - Still uses `websockets` for client connections
+- `/home/pi/lighting-controller/src/ui_client.py` - UI being worked on elsewhere (needs URL update)
+- `/home/pi/led-bar/*` - No changes needed
+