Initial commit: StackPilot Phase 1 (Core)

Self-hosted Docker Compose manager.
- Backend: FastAPI + docker-py + SQLite (JWT auth, file-first stacks,
  lifecycle, live status, WebSocket logs, docker-run converter, audit log)
- Frontend: React + Vite + Tailwind (login/setup, dashboard, stacks,
  stack detail, Monaco editor, dark/light theme)
- Deployment: docker-compose.yml, Dockerfiles, nginx reverse proxy

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

frontend/Dockerfile

@@ -0,0 +1,11 @@
+FROM node:20-alpine AS build
+WORKDIR /app
+COPY package.json ./
+RUN npm install
+COPY . .
+RUN npm run build
+
+FROM nginx:alpine
+COPY nginx.conf /etc/nginx/conf.d/default.conf
+COPY --from=build /app/dist /usr/share/nginx/html
+EXPOSE 80