Move the remaining manual import endpoint logic out of web_server.py and into core.imports.routes behind ImportRouteRuntime. The Flask endpoints now stay as thin compatibility wrappers for album/track search, album match/process, single-file import processing, and batched singles processing.
Keep legacy test patch points intact by re-exporting build_album_import_match_payload from web_server and routing singles_process through an injected process_single_import_file callable. This preserves existing route-level monkeypatch behavior while keeping the extracted helper testable.
Add focused helper coverage for Hydrabase enqueueing, search limit clamping, album match payload forwarding, album import side effects, single-file worker outcomes, malformed manual matches, and singles aggregation/injected-worker behavior.
Verification: py_compile and git diff --check passed locally; bundled-Python smoke covered the extracted helpers. Claude reran the project tests and reported all tests passing.
Move import staging files/groups/hints/suggestions controller logic out of web_server.py and into core.imports.routes behind an ImportRouteRuntime dependency object. Keep the existing Flask routes as thin compatibility wrappers so the UI endpoint surface stays unchanged.
Add focused tests for staging file filtering, album grouping, hint generation, cached suggestions, empty missing staging paths, and error payloads from failed path/metadata reads.
Verification: py_compile passed for web_server.py, core/imports/routes.py, and tests/imports/test_import_routes.py. A bundled-Python smoke pass covered the extracted helper behavior; pytest was not available in this Windows shell because the bundled Python lacks pytest and the repo venv is WSL/Linux-only here.
