feat: Complete Greenhouse API implementation with CLI tools

[rothnic]

Summary

This PR implements complete Greenhouse ATS support using the official Greenhouse Job Board API, adding 129 pre-configured AI/ML employers and comprehensive CLI management tools.

What's Included

Core Greenhouse Integration

• Official API Integration: Uses boards-api.greenhouse.io/v1/boards/{token}/jobs endpoint for reliable, structured job data
• Full Job Descriptions: Retrieves complete job descriptions with ?content=true parameter
• Rich Job Data: Captures job_id, updated_at, offices, department, and full descriptions
• User Customization: Supports ~/.applypilot/greenhouse.yaml for custom employer lists
• Robust Error Handling: Retry logic for rate limits and graceful degradation

CLI Management Tools (5 Commands)

# Verify a company works with our implementation
applypilot greenhouse verify stripe

# Discover correct slugs from company names or URLs
applypilot greenhouse discover "Notion"
applypilot greenhouse discover --url https://careers.company.com

# Validate your entire employer configuration
applypilot greenhouse validate

# Add a specific job by URL
applypilot greenhouse add-job https://boards.greenhouse.io/stripe/jobs/12345 --dry-run

Pre-configured Employers

• 129 Greenhouse ATS employers organized by category:
  • Core AI/ML: Scale AI, Anthropic, Cohere, etc.
  • Infrastructure: Stripe, Datadog, Cloudflare, MongoDB, etc.
  • Fintech: Robinhood, Coinbase, Plaid, Brex, etc.
  • And more categories

Test Coverage

✅ 25 tests passing

• API response parsing
• Job storage and deduplication
• Location and query filtering
• End-to-end integration

Verified Working

• ✅ Successfully fetches 173+ jobs from Scale AI
• ✅ CLI commands all functional
• ✅ Jobs integrate with enrichment/scoring pipeline
• ✅ Full descriptions stored for tailoring

Files Added/Modified

src/applypilot/discovery/greenhouse.py      # Core API implementation
tests/discovery/test_greenhouse.py          # Comprehensive test suite
src/applypilot/cli.py                        # CLI integration
src/applypilot/cli_greenhouse/__init__.py   # 5 CLI management tools
src/applypilot/config/greenhouse.yaml       # 129 employer configurations
CHANGELOG.md                                 # Documented changes
README.md                                    # Added to supported sources

New Dependencies

None. Uses existing project dependencies (httpx, pyyaml, typer).

Breaking Changes

None. This is a pure addition - all existing functionality remains unchanged.

Usage Example

# Run discovery including Greenhouse employers
applypilot run discover

# Validate your employer list
applypilot greenhouse validate

# Add a specific job you found
applypilot greenhouse add-job https://boards.greenhouse.io/scaleai/jobs/4413274005

# Continue with pipeline
applypilot run enrich score tailor

Notes

• Greenhouse integration runs automatically during the discover stage
• Jobs are deduplicated across all sources (Greenhouse, Workday, JobSpy, etc.)
• All jobs feed into the same enrichment/scoring/tailoring pipeline