Rewrite Tracks application in Golang

This commit introduces a complete rewrite of the Tracks GTD application
in Go (Golang), providing a modern, performant alternative to the Ruby
on Rails implementation.

## Architecture & Technology Stack

- Language: Go 1.21+
- Web Framework: Gin
- ORM: GORM with SQLite/MySQL/PostgreSQL support
- Authentication: JWT with bcrypt password hashing
- Clean Architecture: Separated models, services, handlers, and middleware

## Implemented Features

### Core Models
- User: Authentication and user management
- Context: GTD contexts (@home, @work, etc.)
- Project: Project grouping and tracking
- Todo: Task management with state machine (active, completed, deferred, pending)
- Tag: Flexible tagging system with polymorphic associations
- Dependency: Todo dependencies with circular dependency detection
- Preference: User preferences and settings
- Note: Project notes
- Attachment: File attachment support (model only)
- RecurringTodo: Recurring task template (model only)

### API Endpoints

**Authentication:**
- POST /api/auth/login - User login
- POST /api/auth/register - User registration
- POST /api/auth/logout - User logout
- GET /api/me - Get current user

**Todos:**
- GET /api/todos - List todos with filtering
- POST /api/todos - Create todo
- GET /api/todos/:id - Get todo details
- PUT /api/todos/:id - Update todo
- DELETE /api/todos/:id - Delete todo
- POST /api/todos/:id/complete - Mark as completed
- POST /api/todos/:id/activate - Mark as active
- POST /api/todos/:id/defer - Defer to future date
- POST /api/todos/:id/dependencies - Add dependency
- DELETE /api/todos/:id/dependencies/:successor_id - Remove dependency

**Projects:**
- GET /api/projects - List projects
- POST /api/projects - Create project
- GET /api/projects/:id - Get project details
- PUT /api/projects/:id - Update project
- DELETE /api/projects/:id - Delete project
- POST /api/projects/:id/complete - Complete project
- POST /api/projects/:id/activate - Activate project
- POST /api/projects/:id/hide - Hide project
- POST /api/projects/:id/review - Mark as reviewed
- GET /api/projects/:id/stats - Get project statistics

**Contexts:**
- GET /api/contexts - List contexts
- POST /api/contexts - Create context
- GET /api/contexts/:id - Get context details
- PUT /api/contexts/:id - Update context
- DELETE /api/contexts/:id - Delete context
- POST /api/contexts/:id/hide - Hide context
- POST /api/contexts/:id/activate - Activate context
- POST /api/contexts/:id/close - Close context
- GET /api/contexts/:id/stats - Get context statistics

### Business Logic

**Todo State Management:**
- Active: Ready to work on
- Completed: Finished tasks
- Deferred: Future actions (show_from date)
- Pending: Blocked by dependencies

**Dependency Management:**
- Create blocking relationships between todos
- Automatic state transitions when blocking todos complete
- Circular dependency detection
- Automatic unblocking when prerequisites complete

**Tag System:**
- Polymorphic tagging for todos and recurring todos
- Automatic tag creation on first use
- Tag cloud support

**Project & Context Tracking:**
- State management (active, hidden, closed/completed)
- Statistics and health indicators
- Review tracking for projects

### Infrastructure

**Configuration:**
- Environment-based configuration
- Support for SQLite, MySQL, and PostgreSQL
- Configurable JWT secrets and token expiry
- Flexible server settings

**Database:**
- GORM for ORM
- Automatic migrations
- Connection pooling
- Multi-database support

**Authentication & Security:**
- JWT-based authentication
- Bcrypt password hashing
- Secure cookie support
- Token refresh mechanism

**Docker Support:**
- Multi-stage Dockerfile for optimized builds
- Docker Compose with PostgreSQL
- Volume mounting for data persistence
- Production-ready configuration

## Project Structure

```
cmd/tracks/              # Application entry point
internal/
  config/               # Configuration management
  database/             # Database setup and migrations
  handlers/             # HTTP request handlers
  middleware/           # Authentication middleware
  models/              # Database models
  services/            # Business logic layer
```

## Documentation

- README_GOLANG.md: Comprehensive documentation
- .env.example: Configuration template
- API documentation included in README
- Code comments for complex logic

## Future Work

The following features from the original Rails app are not yet implemented:
- Recurring todo instantiation logic
- Email integration (Mailgun/CloudMailin)
- Advanced statistics and analytics
- Import/Export functionality (CSV, YAML, XML)
- File upload handling for attachments
- Mobile views
- RSS/Atom feeds
- iCalendar export

## Benefits Over Rails Version

- Performance: Compiled binary, lower resource usage
- Deployment: Single binary, no runtime dependencies
- Type Safety: Compile-time type checking
- Concurrency: Better handling of concurrent requests
- Memory: Lower memory footprint
- Portability: Easy cross-platform compilation

## Testing

The code structure supports testing, though tests are not yet implemented.
Future work includes adding unit and integration tests.

docker-compose.yml

@@ -1,29 +1,45 @@
-version: '3'
+version: '3.8'
+
 services:
-  db:
-    image: mariadb:lts
-    environment:
-      MARIADB_ALLOW_EMPTY_ROOT_PASSWORD: 1
-      MARIADB_DATABASE: ${TRACKS_DB:-tracks}
-    volumes:
-      - db-data:/var/lib/mysql
-  web:
+  tracks:
     build:
       context: .
-      target: production # can also be development or test
-    environment:
-      # These are set in script/ci-build, so we need to pass-thru them.
-      RAILS_ENV: $RAILS_ENV
-      DATABASE_NAME: $DATABASE_NAME
-      DATABASE_USERNAME: root
-      DATABASE_PASSWORD_EMPTY: 1
-    volumes:
-      - ${VOLUME:-.}:/app:Z
-      - ${VOLUME:-.}/config/database.docker.yml:/app/config/database.yml:Z
-      - ${VOLUME:-.}/config/site.docker.yml:/app/config/site.yml:Z
+      dockerfile: Dockerfile
+    container_name: tracks-go
     ports:
-      - 3000:3000
+      - "3000:3000"
+    environment:
+      - SERVER_HOST=0.0.0.0
+      - SERVER_PORT=3000
+      - GIN_MODE=release
+      - DB_DRIVER=postgres
+      - DB_HOST=postgres
+      - DB_PORT=5432
+      - DB_NAME=tracks
+      - DB_USER=tracks
+      - DB_PASSWORD=tracks
+      - DB_SSLMODE=disable
+      - JWT_SECRET=change-this-in-production
+      - OPEN_SIGNUPS=true
+    volumes:
+      - ./data:/app/data
+      - ./uploads:/app/uploads
     depends_on:
-      - db
+      - postgres
+    restart: unless-stopped
+
+  postgres:
+    image: postgres:16-alpine
+    container_name: tracks-postgres
+    environment:
+      - POSTGRES_DB=tracks
+      - POSTGRES_USER=tracks
+      - POSTGRES_PASSWORD=tracks
+    volumes:
+      - postgres_data:/var/lib/postgresql/data
+    ports:
+      - "5432:5432"
+    restart: unless-stopped
+
 volumes:
-  db-data:
+  postgres_data: