initial agent-mgr: app builder platform MVP

Go API server + Preact UI + Claude Code adapter.
- App-centric model (ideas, not repos)
- AgentProvider interface for multi-agent support
- K8s pod lifecycle for sandboxed agent sessions
- Gitea integration (create repos, push branches)
- WebSocket streaming for live session output
- Woodpecker CI/CD pipelines (kaniko build + kubectl deploy)

docker/Dockerfile.claude-runner

@@ -0,0 +1,17 @@
+FROM node:22-slim
+
+RUN apt-get update && apt-get install -y --no-install-recommends \
+    git \
+    ca-certificates \
+  && rm -rf /var/lib/apt/lists/*
+
+RUN npm install -g @anthropic-ai/claude-code
+
+RUN useradd -m -s /bin/bash agent
+USER agent
+WORKDIR /workspace
+
+COPY --chown=agent:agent entrypoint.sh /usr/local/bin/entrypoint.sh
+RUN chmod +x /usr/local/bin/entrypoint.sh
+
+ENTRYPOINT ["/usr/local/bin/entrypoint.sh"]