chore: update backend tests

backend/tests/api/test_tasks.py

@@ -1,5 +1,10 @@
-# ... (same header as before)
-
+# #region Test.Api.Tasks [C:3] [TYPE Module] [SEMANTICS test,tasks,api,routes,crud]
+# @BRIEF API contract tests for task routes — create, list, get, update, cancel, and provider binding.
+# @RELATION BINDS_TO -> [TasksApi]
+# @TEST_EDGE: missing_plugin_id -> 400 when plugin_id missing
+# @TEST_EDGE: invalid_method -> 405 for unsupported HTTP method
+# @TEST_EDGE: task_not_found -> 404 for nonexistent task
+# @TEST_EDGE: unauthorized_access -> 401 when no auth token
 import os
 
 os.environ.setdefault("DATABASE_URL", "sqlite:///:memory:")