Add LocationRepository with CRUD operations, hierarchy traversal
(children, subtree by path prefix), and inventory-safe deletion.
Endpoints:
GET /api/locations — list all or ?tree={path} for subtree
POST /api/locations — create (auto-resolves parent_id, depth)
GET /api/locations/{path..} — get by hierarchical path
PUT /api/locations/{path..} — update name, type, metadata
DELETE /api/locations/{path..} — delete (rejects if inventory exists)
Uses chi wildcard routes to support multi-segment paths like
/api/locations/lab/shelf-a/bin-3.
Includes 10 handler integration tests covering CRUD, nesting,
validation, duplicates, tree queries, and delete-not-found.
Closes#81
4ef912cf4b