refactor(routes): move admin_wipe domain into routes/admin_wipe/ subpackage (#5659)

Slice 2h of the route-domain reorganization (#4082/#4071). Moves
admin_wipe_routes.py into routes/admin_wipe/, leaving a backward-compat
sys.modules shim at the old path. Pure file reorganization, no behavior
change.

The shim uses sys.modules replacement so the `import ... as
admin_wipe_routes` + `monkeypatch.setattr(admin_wipe_routes, "SessionLocal",
...)` / `"require_admin"` pattern in test_admin_wipe_gallery.py reaches
the canonical module.

Canonical module imports only from core/, src/, and stdlib (zero internal
routes/ coupling). Zero source-introspection landmines.

Adds tests/test_admin_wipe_routes_shim.py to pin the sys.modules shim
contract. Verified: compileall clean; targeted tests pass.

tests/test_admin_wipe_routes_shim.py

@@ -0,0 +1,25 @@
+"""Regression test for the admin_wipe route shim (slice 2h, #4082/#4071).
+
+The backward-compat shim at ``routes/admin_wipe_routes.py`` uses
+``sys.modules`` replacement so the legacy import path and the canonical
+``routes.admin_wipe.*`` path resolve to the *same* module object. This is
+required because ``test_admin_wipe_gallery.py`` does
+``import routes.admin_wipe_routes`` followed by
+``monkeypatch.setattr(routes.admin_wipe_routes, "SessionLocal", ...)`` and
+``"require_admin"`` — for those patches to take effect at runtime, the legacy
+module object and the canonical one must be identical.
+"""
+
+import importlib
+
+import routes.admin_wipe_routes as _shim_admin_wipe  # noqa: F401
+
+
+def test_legacy_and_canonical_admin_wipe_module_are_same_object():
+    """``import routes.admin_wipe_routes`` must alias the canonical module."""
+    legacy = importlib.import_module("routes.admin_wipe_routes")
+    canonical = importlib.import_module("routes.admin_wipe.admin_wipe_routes")
+    assert legacy is canonical, (
+        "routes.admin_wipe_routes shim must resolve to the canonical "
+        "routes.admin_wipe.admin_wipe_routes module object"
+    )