refactor(routes): move document domain into routes/document/ subpackage (#5885)

Slice 2m of the route-domain reorganization (#4082/#4071, per
specs/architecture-runtime-inventory.md §6.3). Moves document_routes.py
(1810 lines) and document_helpers.py (243 lines) into routes/document/,
leaving backward-compat sys.modules shims at the old paths. Pure file
reorganization, no behavior change.

Both shims use sys.modules replacement so the `import ... as droutes` +
`droutes.SessionLocal = ...` / `monkeypatch.setattr(droutes, ...)` pattern
in multiple tests, and the `sys.modules.pop("routes.document_helpers")` +
re-import pattern in test_security_regressions.py, all reach the canonical
modules.

The canonical document_routes.py imports helpers from the canonical path
(routes.document.document_helpers), not the legacy shim.

Three source-introspection test sites repointed to the new canonical path:
- test_imap_mailbox_quoting.py
- test_model_helper_owner_scope.py
- test_vision_owner_scope.py (shared with other domains; document entry repointed)

Adds tests/test_document_routes_shim.py to pin the sys.modules shim contract
for both modules.

Verified: compileall clean; full suite 4789 passed, 3 skipped.

tests/test_document_routes_shim.py

@@ -0,0 +1,29 @@
+"""Regression test for the document route shim (slice 2m, #4082/#4071).
+
+The backward-compat shims at ``routes/document_routes.py`` and
+``routes/document_helpers.py`` use ``sys.modules`` replacement so the legacy
+import paths and the canonical ``routes.document.*`` paths resolve to the
+*same* module objects. This is required because multiple tests do
+``import routes.document_routes as droutes`` followed by
+``droutes.SessionLocal = ...`` / ``monkeypatch.setattr(droutes, ...)`` and
+``sys.modules.pop("routes.document_helpers")`` + re-import — for those to
+take effect at runtime, the legacy and canonical module objects must be
+identical.
+"""
+
+import importlib
+
+import routes.document_routes as _shim_routes  # noqa: F401
+import routes.document_helpers as _shim_helpers  # noqa: F401
+
+
+def test_legacy_and_canonical_routes_are_same_object():
+    legacy = importlib.import_module("routes.document_routes")
+    canonical = importlib.import_module("routes.document.document_routes")
+    assert legacy is canonical
+
+
+def test_legacy_and_canonical_helpers_are_same_object():
+    legacy = importlib.import_module("routes.document_helpers")
+    canonical = importlib.import_module("routes.document.document_helpers")
+    assert legacy is canonical

tests/test_imap_mailbox_quoting.py

@@ -87,7 +87,7 @@ def test_known_imap_mailbox_call_sites_are_quoted():
     assert "conn.select(sent_name" not in pollers
     assert "imap.append(sent_folder" not in pollers
 
-    document_routes = Path("routes/document_routes.py").read_text()
+    document_routes = Path("routes/document/document_routes.py").read_text()
     assert "conn.select(doc.source_email_folder" not in document_routes
 
 

tests/test_model_helper_owner_scope.py

@@ -14,7 +14,7 @@ def _function_source(path: str, name: str) -> str:
 
 
 def test_document_ai_tidy_resolves_with_owner_scope():
-    body = _function_source("routes/document_routes.py", "ai_tidy_documents")
+    body = _function_source("routes/document/document_routes.py", "ai_tidy_documents")
     assert "resolve_task_endpoint(owner=user or None)" in body
     assert 'resolve_endpoint("default", owner=user or None)' in body
 

tests/test_vision_owner_scope.py

@@ -88,7 +88,7 @@ def test_request_vision_call_sites_pass_owner():
     chat_source = (ROOT / "src" / "chat_handler.py").read_text()
     processor_source = (ROOT / "src" / "document_processor.py").read_text()
     upload_source = (ROOT / "routes" / "upload_routes.py").read_text()
-    document_source = (ROOT / "routes" / "document_routes.py").read_text()
+    document_source = (ROOT / "routes" / "document" / "document_routes.py").read_text()
     gallery_source = (ROOT / "routes" / "gallery" / "gallery_routes.py").read_text()
     memory_source = (ROOT / "routes" / "memory" / "memory_routes.py").read_text()