Add self-update feature via GitHub Releases

Checks for updates on startup (silent, badge on button if available)
and on manual click. Downloads new portable .exe to temp dir, creates
a batch script to swap the running executable after quit, then relaunches.

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

README.md

@@ -10,6 +10,7 @@ An Electron desktop application for managing Alta Video camera proxy connections
 - **Device Filtering**: Automatically filters to show only local (non-cloud) cameras
 - **Device Search**: Quick search functionality to find cameras by name, ID, IP, or model
 - **Real-time Status**: Live connection status and device online/offline indicators
+- **Auto-Update**: Checks for updates on startup via GitHub Releases, with one-click in-place update
 - **Modern Dark UI**: Professional dark-mode interface with responsive design
 
 ## Prerequisites
@@ -64,6 +65,14 @@ npm run dev
 3. **Click "Start Camera Proxy"**
 4. A command prompt window will open with the proxy connection
 
+### Updating
+
+The app checks for updates automatically 2 seconds after launch. If a newer version is available on GitHub Releases, the "Check for Updates" button in the header will show a green badge.
+
+- **Manual check**: Click "Check for Updates" in the top-right corner
+- **Install**: The update modal shows release notes — click "Install Update" to download and replace the current executable
+- The app will quit, swap the `.exe`, and relaunch automatically
+
 ## API Endpoints Used
 
 - **Device List**: `GET /api/v1/devices` — Retrieve all devices
@@ -154,6 +163,7 @@ npm run build
 - **Local Cameras Only**: Automatically filters out cloud-based cameras
 - **No Session Refresh**: Sessions may expire and require re-import from Chrome
 - **Executable Required**: `aware-cam-proxy.exe` must be obtained separately
+- **Update Requires Write Access**: Self-update needs write permission to the directory containing the `.exe`
 
 ## Development