施工(HEL-226): 实现登录门户与本机免密切换账号

用设备 Cookie 和授权表记住本机已验证账号，登录页按确认样图做成门户，不再把密码写进浏览器。

Co-authored-by: Cursor <cursoragent@cursor.com>
Co-authored-by: multica-agent <github@multica.ai>

tests/test_database_migrations.py

@@ -25,6 +25,7 @@ class DatabaseMigrationTests(unittest.TestCase):
                         ("0002", "create_job_runs"),
                         ("0003", "extend_llm_audit"),
                         ("0004", "add_mentor_note"),
+                        ("0005", "create_account_switch_grants"),
                     ],
                 )
                 columns = {
@@ -39,7 +40,7 @@ class DatabaseMigrationTests(unittest.TestCase):
                 count = connection.execute(
                     "SELECT COUNT(*) AS count FROM schema_migrations"
                 ).fetchone()["count"]
-            self.assertEqual(count, 4)
+            self.assertEqual(count, 5)
 
     def test_database_with_recorded_0004_and_note_column_starts_without_reapply(
         self,
@@ -60,7 +61,7 @@ class DatabaseMigrationTests(unittest.TestCase):
                 count = connection.execute(
                     "SELECT COUNT(*) AS count FROM schema_migrations"
                 ).fetchone()["count"]
-            self.assertEqual(count, 4)
+            self.assertEqual(count, 5)
 
     def test_old_database_without_0004_upgrades_and_adds_note_column(self) -> None:
         with tempfile.TemporaryDirectory() as root:
@@ -87,7 +88,7 @@ class DatabaseMigrationTests(unittest.TestCase):
                         "PRAGMA table_info(mentor_preferences)"
                     )
                 ]
-            self.assertEqual(versions, {"0001", "0002", "0003", "0004"})
+            self.assertEqual(versions, {"0001", "0002", "0003", "0004", "0005"})
             self.assertIn("note", note_rows)
 
     def test_database_with_unknown_migration_is_rejected(self) -> None: