refactor(routes): move cleanup domain into routes/cleanup/ subpackage

[ydonghao]

Summary

Slice 2g of the route-domain reorganization (Refs #4082 / #4071; inventory baseline in #4148). Moves the cleanup domain into routes/cleanup/, keeping a backward-compat sys.modules shim at the old path. Pure file reorganization, no behavior change.

Follows the same pattern as the merged gallery (#4903), research (#4975), memory (#5007), history (#5090), contacts (#5227), and note (#5236) slices.

What moves

From	To
routes/cleanup_routes.py (60 lines)	routes/cleanup/cleanup_routes.py

New routes/cleanup/__init__.py marks the subpackage. Cleanup is a single-file, LOW-complexity domain with zero internal routes/ coupling.

Backward compatibility

A backward-compat shim remains at routes/cleanup_routes.py, using sys.modules replacement so string-targeted monkeypatch.setattr("routes.cleanup_routes.*", ...) in test_cleanup_owner_scope.py reaches the canonical module.

The canonical module imports only from src/ and stdlib — no dependency on the legacy shim.

Test repoints

Zero source-introspection landmines. No test reads this file by path.

Shim regression test

Adds tests/test_cleanup_routes_shim.py to pin the sys.modules shim contract (same-object).

How to test

python -m compileall routes/cleanup/ routes/cleanup_routes.py app.py
python -m pytest tests/ -q

Target branch

• This PR targets dev, not main.

Linked Issue

Follows the Phase 0 architecture refactor (#4082 / #4071) and the merged runtime inventory (#4148). One domain per PR per maintainer guidance.

Type of Change

• Refactor / cleanup

Checklist

• I searched open issues and open PRs — this is not a duplicate
• This PR targets dev
• My changes are limited to the scope described above — no unrelated refactors
• No runtime behavior changes (pure file move + import shim)
• Backward-compatible: old from routes.cleanup_routes import ... paths keep working via shim

[ydonghao]

Friendly ping for review 👋

This is slice 2g of the route-domain reorg, one of three parallel low-risk slices (the others: #5659 admin_wipe, #5660 compare). Only the cleanup domain moves — a single-file, 60-line domain with zero internal routes/ coupling — into routes/cleanup/ behind the same sys.modules shim as all previous slices.

Both points from your #4903 review are baked in (canonical doesn't depend on shim; shim regression test included). Zero source-introspection landmines. CI fully green (pytest 4676 passed).

@RaresKeY @alteixeira20 — would you mind taking a look when you have a moment?

[RaresKeY]

LGTM

I checked the latest head against the prior route-domain move pattern and the linked architecture cleanup context. The moved cleanup route implementation is byte-for-byte preserved under the canonical package path, app registration uses that path, and the legacy routes.cleanup_routes shim keeps old imports and monkeypatch-based owner-scope tests on the same module object.

Validation looked solid: GitHub checks are green, the focused cleanup owner/shim tests and changed-file compile checks pass, the app mounts both cleanup routes through the canonical module, and I did not find any blocking issues.