fix(api): attribute bearer-token actions to the token owner on owner-scoped routes (#4054)

* fix(api): attribute bearer-token actions to the token owner on owner-scoped routes

Owner-scoped chat, session, and upload routes called
get_current_user(), which resolves a bearer ody_ API token to the
sandboxed "api" pseudo-user. A paired API-token client (companion, CLI,
IDE extension) therefore saw and created a separate "api"-owned silo
instead of the owner's data.

effective_user() already exists for exactly this: it attributes a token's
actions to request.state.api_token_owner, is identical to
get_current_user() for cookie sessions, and falls back safely when a
token has no owner. session_routes.py was already migrated; this
completes the migration for the remaining owner-scoped routes:

- chat_helpers.py: chat-privilege enforcement, message attribution, prefs/context
- chat_routes.py: orphaned-endpoint owner, session-auth owner, message search
- upload_routes.py: upload owner attribution + access checks

The /api/models swap is intentionally omitted: #4292 already migrated it
to effective_user (plus the chat-scope gate and ownerless-token 403), so
this PR keeps dev's version of routes/model_routes.py unchanged.

chat_routes.py keeps importing get_current_user for the workspace owner
gate; session_routes.py drops the now-unused import.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

* test: target effective_user in auth monkeypatches and owner-scope assertion

The owner-scoped routes now call effective_user() instead of
get_current_user(), so the tests that stubbed get_current_user (or
asserted on it) follow suit:

- test_chat_helpers.py, test_review_regressions.py,
  test_kv_cache_invalidation_2927.py: monkeypatch effective_user
- test_session_endpoint_owner_scope.py: assert the owner-scope guard uses
  effective_user(request)

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>

tests/test_chat_helpers.py

@@ -30,7 +30,7 @@ class _Session:
 
 
 def test_allowed_models_legacy_empty_list_remains_unrestricted(monkeypatch):
-    monkeypatch.setattr("routes.chat_helpers.get_current_user", lambda request: "alice")
+    monkeypatch.setattr("routes.chat_helpers.effective_user", lambda request: "alice")
 
     _enforce_chat_privileges(
         _Request({"allowed_models": [], "max_messages_per_day": 0}),
@@ -39,7 +39,7 @@ def test_allowed_models_legacy_empty_list_remains_unrestricted(monkeypatch):
 
 
 def test_allowed_models_explicit_empty_restricted_list_blocks_all_models(monkeypatch):
-    monkeypatch.setattr("routes.chat_helpers.get_current_user", lambda request: "alice")
+    monkeypatch.setattr("routes.chat_helpers.effective_user", lambda request: "alice")
 
     with pytest.raises(HTTPException) as exc:
         _enforce_chat_privileges(
@@ -56,7 +56,7 @@ def test_allowed_models_explicit_empty_restricted_list_blocks_all_models(monkeyp
 
 
 def test_allowed_models_nonempty_list_still_restricts_without_new_flag(monkeypatch):
-    monkeypatch.setattr("routes.chat_helpers.get_current_user", lambda request: "alice")
+    monkeypatch.setattr("routes.chat_helpers.effective_user", lambda request: "alice")
 
     _enforce_chat_privileges(
         _Request({"allowed_models": ["provider/model-a"], "max_messages_per_day": 0}),
@@ -70,7 +70,7 @@ def test_allowed_models_nonempty_list_still_restricts_without_new_flag(monkeypat
 
 
 def test_no_restriction_allows_any_model(monkeypatch):
-    monkeypatch.setattr("routes.chat_helpers.get_current_user", lambda request: "alice")
+    monkeypatch.setattr("routes.chat_helpers.effective_user", lambda request: "alice")
 
     privs = {"allowed_models": [], "block_all_models": False, "max_messages_per_day": 0}
     _enforce_chat_privileges(_Request(privs), _Session("provider/model-a"))
@@ -78,7 +78,7 @@ def test_no_restriction_allows_any_model(monkeypatch):
 
 
 def test_specific_allowlist_blocks_models_outside_it(monkeypatch):
-    monkeypatch.setattr("routes.chat_helpers.get_current_user", lambda request: "alice")
+    monkeypatch.setattr("routes.chat_helpers.effective_user", lambda request: "alice")
 
     privs = {
         "allowed_models": ["gpt-4"],
@@ -92,7 +92,7 @@ def test_specific_allowlist_blocks_models_outside_it(monkeypatch):
 
 
 def test_block_all_models_blocks_regardless_of_allowed_models_contents(monkeypatch):
-    monkeypatch.setattr("routes.chat_helpers.get_current_user", lambda request: "alice")
+    monkeypatch.setattr("routes.chat_helpers.effective_user", lambda request: "alice")
 
     # Even if allowed_models contains entries, block_all_models wins.
     privs = {
@@ -111,7 +111,7 @@ def test_block_all_models_blocks_regardless_of_allowed_models_contents(monkeypat
 def test_admin_user_is_never_blocked(monkeypatch):
     from core.auth import ADMIN_PRIVILEGES
 
-    monkeypatch.setattr("routes.chat_helpers.get_current_user", lambda request: "admin")
+    monkeypatch.setattr("routes.chat_helpers.effective_user", lambda request: "admin")
 
     class _AdminAuthManager:
         def get_privileges(self, username):