Complete Phase 6: Docker deployment and CI/CD

Health Checks (6.3):
- Add is_healthy property and get_health_status() to Receiver/Sender
- Add is_healthy property and get_health_status() to Collector Subscriber
- Track device, MQTT, and database connection status

Documentation (6.5):
- Update README with Docker Compose profiles documentation
- Add serial device access instructions
- Update API documentation URLs and add health check info

CI/CD (6.6):
- Add .github/workflows/ci.yml for linting, testing, and building
- Add .github/workflows/docker.yml for Docker image builds
- Support Python 3.11 and 3.12 in CI matrix
- Configure Codecov for coverage reporting

End-to-End Testing (6.7):
- Add tests/e2e/ directory with Docker Compose test configuration
- Add e2e test fixtures with service health waiting
- Add comprehensive e2e tests for API, Web, and auth flows

.github/workflows/docker.yml

@@ -0,0 +1,65 @@
+name: Docker
+
+on:
+  push:
+    branches: [main, master]
+    tags:
+      - "v*"
+  pull_request:
+    branches: [main, master]
+
+env:
+  REGISTRY: ghcr.io
+  IMAGE_NAME: ${{ github.repository }}
+
+jobs:
+  build:
+    name: Build Docker Image
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+      packages: write
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+
+      - name: Log in to Container Registry
+        if: github.event_name != 'pull_request'
+        uses: docker/login-action@v3
+        with:
+          registry: ${{ env.REGISTRY }}
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Extract metadata for Docker
+        id: meta
+        uses: docker/metadata-action@v5
+        with:
+          images: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
+          tags: |
+            type=ref,event=branch
+            type=ref,event=pr
+            type=semver,pattern={{version}}
+            type=semver,pattern={{major}}.{{minor}}
+            type=sha
+
+      - name: Build and push Docker image
+        uses: docker/build-push-action@v5
+        with:
+          context: .
+          file: docker/Dockerfile
+          push: ${{ github.event_name != 'pull_request' }}
+          tags: ${{ steps.meta.outputs.tags }}
+          labels: ${{ steps.meta.outputs.labels }}
+          cache-from: type=gha
+          cache-to: type=gha,mode=max
+
+      - name: Test Docker image
+        if: github.event_name == 'pull_request'
+        run: |
+          docker build -t meshcore-hub-test -f docker/Dockerfile .
+          docker run --rm meshcore-hub-test --version
+          docker run --rm meshcore-hub-test --help