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/user-profile/spec.md

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+# User Profile Management Specification
+
+## Purpose
+
+Manage user profiles including personal information and avatar.
+
+## Requirements
+
+### Requirement: Profile Retrieval
+
+The system SHALL allow users to view their profile.
+
+#### Scenario: View profile
+- GIVEN an authenticated user
+- WHEN they access the profile page
+- THEN their name, email, and avatar are displayed
+
+### Requirement: Profile Updates
+
+The system SHALL allow users to update their profile.
+
+#### Scenario: Update name and email
+- GIVEN an authenticated user
+- WHEN they submit profile changes
+- THEN the system validates the input
+- AND updates the user record
+
+### Requirement: Avatar Upload
+
+The system SHALL support local avatar storage.
+
+#### Scenario: Upload avatar
+- GIVEN an authenticated user
+- WHEN they upload an image file
+- THEN the system validates the file type and size
+- AND stores it locally
+- AND updates the user's avatar URL
+
+## Dependencies
+
+- auth-oauth (authenticated users)
+- Database models: User
+
+## Quality Gates
+
+- `pytest` must pass
+- `mypy .` must pass
+- `ruff check .` must pass
+- `npm run typecheck` must pass
+- `npm run lint` must pass