Replace unbounded thread spawning with managed worker pool:
- New pypi_cache_tasks table tracks caching jobs
- Thread pool with 5 workers (configurable via ORCHARD_PYPI_CACHE_WORKERS)
- Automatic retries with exponential backoff (30s, 60s, then fail)
- Deduplication to prevent duplicate caching attempts
New API endpoints for visibility and control:
- GET /pypi/cache/status - queue health summary
- GET /pypi/cache/failed - list failed tasks with errors
- POST /pypi/cache/retry/{package} - retry single package
- POST /pypi/cache/retry-all - retry all failed packages
This fixes silent failures in background dependency caching where
packages would fail to cache without any tracking or retry mechanism.
- Go server with Gin framework
- PostgreSQL for metadata storage
- MinIO/S3 for artifact storage with SHA256 content addressing
- REST API for grove/tree/fruit operations
- Web UI for managing artifacts
- Docker Compose setup for local development
