Add connection overlay and Gitea CI/CD workflow

Show full-screen overlay with spinner when server is unreachable,
with periodic health checks that auto-hide on reconnect.
Add Gitea Actions workflow for auto-deploy on release tags.

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

.gitea/workflows/deploy.yml

@@ -0,0 +1,31 @@
+name: Build and Deploy
+
+on:
+  push:
+    tags:
+      - 'v*'
+
+jobs:
+  deploy:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Deploy to /opt/wled-controller
+        run: |
+          DEPLOY_DIR=/opt/wled-controller
+
+          # Ensure deploy directory exists
+          mkdir -p "$DEPLOY_DIR/data" "$DEPLOY_DIR/logs" "$DEPLOY_DIR/config"
+
+          # Copy server files to deploy directory
+          rsync -a --delete \
+            --exclude 'data/' \
+            --exclude 'logs/' \
+            server/ "$DEPLOY_DIR/"
+
+          # Build and restart
+          cd "$DEPLOY_DIR"
+          docker compose down
+          docker compose up -d --build