Add local Docker deployment support

[sbafsk]

Summary

This PR adds comprehensive Docker support for local deployment, following Docker best practices.

Features

Docker Compose Setup

• PostgreSQL 15 Alpine with multi-database support (primary, cache, queue, cable)
• Rails 8 with Thruster for production-ready HTTP serving
• Solid Queue running inline with Puma for background jobs
• Health checks for both web and database services
• Resource limits (512M memory) for container management
• tmpfs for cache/pids to reduce disk I/O

Dockerfile Improvements

• Multi-stage build (base → build → production)
• Official Ruby 3.3.6 slim image
• Non-root user with explicit UID/GID 1000
• jemalloc for memory optimization
• OCI image labels for metadata
• Comprehensive .dockerignore

New Files

• docker-compose.yml - Full Docker Compose configuration
• docker/init-databases.sh - Script to create additional PostgreSQL databases
• docs/guides/local-docker-deployment.md - Deployment guide
• .env.example - Template for required environment variables

Quick Start

# Setup
cp .env.example .env
# Edit .env with RAILS_MASTER_KEY from config/master.key

# Build and run
docker-compose build
docker-compose up -d

# Access at http://localhost:3003

Best Practices Applied

Practice	Implementation
Multi-stage builds	✅ 3 stages
Official base images	✅ ruby:3.3.6-slim
Non-root USER	✅ UID/GID 1000
Health checks	✅ Both services
Resource limits	✅ 512M memory
Layer caching	✅ Gemfile first
.dockerignore	✅ Comprehensive

Testing

• docker-compose build succeeds
• docker-compose up -d starts both services
• Health checks pass (both show "healthy")
• App accessible at http://localhost:3003
• Seeds load correctly (14 projects, 49 tasks)
• Solid Queue starts inline with Puma

[Copilot]

Pull request overview

This PR adds comprehensive Docker support for local deployment of the Task Tracker application, enabling single-command setup and deployment using Docker Compose. The implementation follows Docker best practices with multi-stage builds, health checks, and proper resource management.

Changes:

• Docker Compose configuration with PostgreSQL 15 and Rails 8 services
• Multi-database support for Solid Cache, Queue, and Cable
• Complete deployment documentation and troubleshooting guide
• Real portfolio project data replacing example seed data

Reviewed changes

Copilot reviewed 8 out of 9 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
docker-compose.yml	Defines services for PostgreSQL and Rails web application with health checks and resource limits
docker/init-databases.sh	Initializes additional PostgreSQL databases for Rails 8 Solid components
Dockerfile	Adds OCI image metadata labels
config/database.yml	Adds environment variable configuration for multi-database URLs
.env.example	Template for required environment variables
docs/guides/local-docker-deployment.md	Comprehensive deployment guide with architecture diagrams and troubleshooting
db/seeds.rb	Replaces example data with real portfolio projects and tasks
db/seeds_example.rb	Preserves original example seed data for reference

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