move Docker builds to GitHub Actions, Woodpecker becomes deploy-only

- GHA ci.yml: add build + deploy jobs (push to DockerHub, trigger Woodpecker)
- Drop test matrix to single Python 3.12, preserve mypy step
- Build/deploy gated on push to main (PRs still run tests only)
- Woodpecker: deploy.yml (manual event, kubectl set image + slack notify)
- Old pipeline preserved as build-fallback.yml (manual trigger)

.woodpecker/build-fallback.yml

@@ -0,0 +1,42 @@
+when:
+  - event: manual
+
+clone:
+  git:
+    image: woodpeckerci/plugin-git
+    settings:
+      attempts: 5
+      backoff: 10s
+
+steps:
+  - name: test
+    image: python:3.12-slim
+    commands:
+      - pip install -e ".[api,dev]"
+      - ruff check src/ tests/
+      - pytest tests/ -v --tb=short
+
+  - name: build-and-push
+    image: woodpeckerci/plugin-docker-buildx
+    depends_on:
+      - test
+    settings:
+      username: viktorbarzin
+      password:
+        from_secret: dockerhub-token
+      repo: viktorbarzin/claude-memory-mcp
+      dockerfile: docker/Dockerfile
+      context: .
+      platforms:
+        - linux/amd64
+      tags:
+        - "${CI_PIPELINE_NUMBER}"
+        - latest
+
+  - name: deploy
+    image: bitnami/kubectl:latest
+    depends_on:
+      - build-and-push
+    commands:
+      - kubectl set image deployment/claude-memory claude-memory=viktorbarzin/claude-memory-mcp:${CI_PIPELINE_NUMBER} -n claude-memory
+      - kubectl rollout status deployment/claude-memory -n claude-memory --timeout=120s