feat(container): M-Box 1-8 — stack-agnostic standalone Docker container

Shade now ships as a self-contained Docker image. Deploy one container
per project, any stack (Bun, Python, Go, Rust, Kotlin) can talk to it via
plain HTTP. Zero coupling to consumer codebases.

M-Box 1: Stale identity cleanup API
- touchIdentity + purgeStaleIdentities on PrekeyStore interface
- Implemented for Memory, SQLite, and Postgres backends
- SQLite adds last_activity_at column with migration ALTER for existing DBs
- Postgres adds the same via raw SQL with IF NOT EXISTS guards
- Routes call touchIdentity on register, bundle fetch, replenish
- 4 new tests for the cleanup API

M-Box 2: Stale cleanup background task
- StaleCleanupTask runs purge on startup + every 24h (configurable)
- Reads SHADE_STALE_DAYS (default 30) and SHADE_CLEANUP_INTERVAL_HOURS
- Wired into standalone.ts, stopped on graceful shutdown
- 5 new tests for the task

M-Box 3: Observer baked into the container
- standalone.ts conditionally mounts @shade/observer at /shade-observer
  when SHADE_OBSERVER_TOKEN is set (and >= 16 chars)
- Shared PrekeyServerEvents emitter feeds both routes and observer
- @shade/observer added as optional dependency of @shade/server

M-Box 4: Dockerfile with dashboard build
- Multi-stage build: oven/bun:1 builder → oven/bun:1-alpine runtime
- COPY packages/ wholesale so workspace lockfile resolves cleanly
- RUN bun run build inside shade-dashboard → dist/ → observer/dist/
- Non-root shade user, /data volume, healthcheck, env defaults
- Final image: 260 MB

M-Box 5: OpenAPI spec for stack-agnostic clients
- packages/shade-server/openapi.yaml documents all 9 endpoints with
  request/response schemas, security (Ed25519 signatures + bearer token)
- createOpenApiRoutes serves /openapi.yaml and /docs (Redoc viewer)
- Any language can generate a client with openapi-generator

M-Box 6: Docker CI pipeline
- .gitea/workflows/docker.yml builds + pushes on git tag v*
- scripts/build-docker.ts for local builds, supports --push with GITEA_TOKEN
- Root package.json: build:docker, publish:docker scripts

M-Box 7: Deployment documentation
- packages/shade-server/README rewritten: 5-line quickstart with the image
- docs/DEPLOYMENT.md: full reference, env vars, backup, Dokploy, PG setup
- examples/05-dokploy-deployment/docker-compose.yml updated to pull
  published image (gt.zyon.no/stian/shade-prekey:latest)
- Root README deployment section rewritten

M-Box 8: End-to-end verification
- Image builds locally (bun run build:docker)
- /health, /openapi.yaml, /docs, /metrics, /shade-observer all respond
- 401 without observer token, 200 with
- Real SDK client round-trip: Alice → container → Bob → reply → Alice
- Persistence: identity + prekeys survive container restart (count 20→18
  as expected from two bundle fetches)

285 tests passing, 0 failures.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.gitea/workflows/docker.yml

@@ -0,0 +1,52 @@
+name: Docker build and publish
+
+on:
+  push:
+    tags:
+      - 'v*'
+  workflow_dispatch:
+
+jobs:
+  docker:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Install Bun
+        run: curl -fsSL https://bun.sh/install | bash
+
+      - name: Install dependencies
+        run: ~/.bun/bin/bun install --frozen-lockfile
+
+      - name: Run tests (gate)
+        run: ~/.bun/bin/bun test --recursive
+
+      - name: Extract version from tag
+        id: version
+        run: |
+          VERSION="${GITHUB_REF_NAME#v}"
+          echo "version=$VERSION" >> "$GITHUB_OUTPUT"
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+
+      - name: Log in to Gitea container registry
+        uses: docker/login-action@v3
+        with:
+          registry: gt.zyon.no
+          username: Stian
+          password: ${{ secrets.GITEA_PUBLISH_TOKEN }}
+
+      - name: Build and push
+        uses: docker/build-push-action@v5
+        with:
+          context: .
+          file: packages/shade-server/Dockerfile
+          push: true
+          tags: |
+            gt.zyon.no/stian/shade-prekey:${{ steps.version.outputs.version }}
+            gt.zyon.no/stian/shade-prekey:latest
+          labels: |
+            org.opencontainers.image.version=${{ steps.version.outputs.version }}
+            org.opencontainers.image.source=https://gt.zyon.no/Stian/Shade
+            org.opencontainers.image.revision=${{ github.sha }}