feat: implement docker infrastructure (US-001)

- Add docker-compose.yml with postgres, redis, api, and web services
- Add multi-stage Dockerfile for API (Python 3.11)
- Add multi-stage Dockerfile for web (Node.js 20 + nginx)
- Add Makefile with common development commands
- Add .env.example with all required environment variables
- Add placeholder pyproject.toml and package.json for builds
- Configure health checks for all services
- Setup persistent volumes for postgres, redis, and repos
- Run services as non-root users

openspec/specs/frontend-foundation/spec.md

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+# Frontend Foundation Specification
+
+## Purpose
+
+Provide a modern React frontend with TypeScript, routing, and responsive layout.
+
+## Requirements
+
+### Requirement: React Application Setup
+
+The system SHALL use React 18+ with TypeScript.
+
+#### Scenario: Frontend build
+- GIVEN the frontend codebase
+- THEN it SHALL:
+  - Use React 18+ with TypeScript 5+
+  - Use Vite as the build tool
+  - Support Hot Module Replacement (HMR)
+  - Output optimized production builds
+
+### Requirement: Client-Side Routing
+
+The system SHALL implement client-side routing.
+
+#### Scenario: Navigation
+- GIVEN the frontend application
+- THEN React Router SHALL:
+  - Define routes for all pages
+  - Support protected routes (require authentication)
+  - Handle 404 errors
+  - Support route parameters
+
+#### Scenario: Protected routes
+- GIVEN an unauthenticated user
+- WHEN they access a protected route
+- THEN they are redirected to login
+
+### Requirement: Styling Framework
+
+The system SHALL use Tailwind CSS for styling.
+
+#### Scenario: UI components
+- GIVEN the frontend codebase
+- THEN Tailwind CSS SHALL:
+  - Provide utility-first styling
+  - Support custom theme configuration
+  - Include responsive design utilities
+  - Support dark mode
+
+### Requirement: Layout Component
+
+The system SHALL provide a consistent application layout.
+
+#### Scenario: Application shell
+- GIVEN the frontend application
+- THEN a Layout component SHALL:
+  - Display a header with user info and logout
+  - Display a sidebar with navigation links
+  - Show main content area
+  - Collapse sidebar on mobile
+
+#### Scenario: Navigation links
+- GIVEN the sidebar navigation
+- THEN it SHALL include links to:
+  - Dashboard
+  - Projects
+  - Repositories
+  - SSH Keys
+  - Settings
+
+### Requirement: Responsive Design
+
+The system SHALL support mobile devices.
+
+#### Scenario: Mobile viewport
+- GIVEN a mobile device
+- WHEN the app loads
+- THEN:
+  - A hamburger menu replaces the sidebar
+  - Content adapts to screen width
+  - Touch targets are appropriately sized
+
+### Requirement: Loading States
+
+The system SHALL handle asynchronous operations gracefully.
+
+#### Scenario: Data fetching
+- GIVEN a page loading data
+- THEN:
+  - Loading spinners/skeletons are shown
+  - Error boundaries catch errors
+  - Retry options are available on failure
+
+### Requirement: HTTP Client Configuration
+
+The system SHALL configure HTTP requests properly.
+
+#### Scenario: API communication
+- GIVEN the frontend application
+- THEN Axios/fetch SHALL:
+  - Send credentials (cookies) with requests
+  - Handle 401 responses by redirecting to login
+  - Set appropriate content-type headers
+  - Support request/response interceptors
+
+### Requirement: Dashboard Page
+
+The system SHALL provide a dashboard overview.
+
+#### Scenario: Dashboard view
+- GIVEN an authenticated user
+- WHEN they visit the dashboard
+- THEN they see:
+  - Total repository count
+  - Total project count
+  - Recent activity
+  - Quick action buttons
+
+## Dependencies
+
+- React 18+
+- TypeScript 5+
+- Vite
+- React Router
+- Tailwind CSS
+- Axios
+
+## Quality Gates
+
+- `npm run typecheck` must pass
+- `npm run lint` must pass
+- `npm run build` must succeed
+- Frontend handles 401 responses correctly
+- Responsive design works on mobile