CUB-204: wire WS client as primary, REST poller as fallback

- Rename GatewayURL/GatewayPollInterval → GatewayRestURL/GatewayRestPollInterval
- Change Docker-aware defaults (host.docker.internal instead of localhost)
- Client.Start() waits for WS readiness (30s timeout), falls back to REST
- Client.SetWSClient()/MarkWSReady() for WS→REST coordination
- WSClient.SetRESTClient() so WS notifies REST on successful handshake
- main.go wires both clients: WS primary, REST fallback with cross-references
- .env.example documents WS_GATEWAY_URL, GATEWAY_TOKEN, REST fallback vars
- docker-compose.yml adds WS_GATEWAY_URL and GATEWAY_TOKEN env vars
- reference/CONTROL_CENTER_CONTEXT.md documents architecture and startup sequence

.gitea/workflows/build-dev.yaml

@@ -0,0 +1,85 @@
+name: Build (Dev)
+
+on:
+  push:
+    branches: [dev]
+  pull_request:
+    branches: [dev]
+  workflow_dispatch:
+
+env:
+  GO_VERSION: "1.23"
+  NODE_VERSION: "22"
+  BINARY_NAME: server
+
+jobs:
+  build-go-backend:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Setup Go
+        uses: actions/setup-go@v5
+        with:
+          go-version: ${{ env.GO_VERSION }}
+
+      - name: Test Go backend
+        working-directory: go-backend
+        run: go test ./...
+
+      - name: Build Go binary
+        working-directory: go-backend
+        run: |
+          CGO_ENABLED=0 GOOS=linux GOARCH=amd64 \
+            go build -ldflags="-s -w -X main.version=${GITHUB_SHA:0:8}" \
+            -o ${{ env.BINARY_NAME }} ./cmd/server
+
+      - name: Upload Go binary
+        uses: actions/upload-artifact@v4
+        with:
+          name: go-backend-binary
+          path: go-backend/${{ env.BINARY_NAME }}
+          retention-days: 3
+
+  build-frontend:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Setup Node
+        uses: actions/setup-node@v4
+        with:
+          node-version: ${{ env.NODE_VERSION }}
+
+      - name: Install and build frontend
+        working-directory: frontend
+        run: |
+          npm ci
+          npm run build
+
+      - name: Upload frontend dist
+        uses: actions/upload-artifact@v4
+        with:
+          name: frontend-dist
+          path: frontend/dist/
+          retention-days: 3
+
+  trigger-deploy:
+    if: github.event_name == 'push'
+    needs: [build-go-backend, build-frontend]
+    runs-on: ubuntu-latest
+    steps:
+      - name: Trigger deploy workflow
+        uses: actions/github-script@v7
+        with:
+          github-token: ${{ secrets.GITHUB_TOKEN }}
+          script: |
+            await github.rest.repos.createDispatchEvent({
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              event_type: 'dev-build-success',
+              client_payload: {
+                sha: context.sha,
+                ref: context.ref
+              }
+            })