feat: modernize development tooling with uv dependency-groups and enhanced CI/CD

Comprehensive update to development tooling and CI/CD pipeline using modern Python packaging practices.

Features Added

• UV Dependency Groups: Migrate to uv's native [dependency-groups] for dev dependencies, replacing optional-dependencies
• Enhanced GitLab CI: Add workflow rules for MR/branch triggers, build stage, improved caching, and standardized job descriptions
• Pre-commit Hooks: Add docker validation hooks (docker-compose config, docker build check) with fail-fast mode
• Docker Improvements: Multi-stage Dockerfile build, healthchecks, standardized environment variables with sensible defaults

Dependencies

• Added fastapi-cache and fastapi-pagination for API performance
• Consolidated linting to ruff (replaces black + isort)

Documentation Updated

• CONTRIBUTING.md and docs/INSTALLATION.md: Updated install commands to use uv sync --group dev

Testing

• Verified uv sync --group dev works locally and in CI
• Docker builds successfully with multi-stage setup
• All CI jobs run without errors

Breaking Changes

• Install command changed from uv pip install -e ".[dev]" to uv sync --group dev