Add dependency_inventory.py — an inventory tool that scans repos
for dependency manifests (requirements.txt, package.json,
go.mod, Cargo.toml, pyproject.toml) and produces either
JSON or markdown report.
Includes:
- Full parser suite for 5 manifest types
- --repos and --repos-dir argument support
- Incremental friendly — safe to add new features
- --output/-o file support
- Test suite in tests/test_dependency_inventory.py
Closes#107 (1/5) — first script in the Health Report toolkit.