perf: add GIN indexes on clazz JSONB columns and date-range indexes

- GIN indexes on students/teachers (jsonb_path_ops) for fast user lookups
- Composite index on clazz (is_repeat, start_from, end_by) for date range queries
- Indexes on clazz_repeat (clazz_id, repeat_start, repeat_end) for joins

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

htykc/src/ws_clazz.rs

@@ -966,6 +966,7 @@ mod tests {
             tags: None,
             current_org_id: current_org_id.map(|value| value.to_string()),
             current_org_role_keys: Some(vec!["TEACHER".to_string()]),
+            current_department_id: None,
         };
         jwt_encode_token(token).expect("encode test token")
     }

htykc/src/ws_xiaoke.rs

@@ -337,6 +337,7 @@ mod tests {
             tags: None,
             current_org_id: current_org_id.map(|value| value.to_string()),
             current_org_role_keys: Some(vec!["TEACHER".to_string()]),
+            current_department_id: None,
         };
         AuthorizationHeader(jwt_encode_token(token).expect("encode test token"))
     }

htykc/tests/e2e_clazz_tests.rs

@@ -33,6 +33,7 @@ fn build_test_token(with_org_context: bool) -> String {
             None
         },
         current_org_role_keys: Some(vec!["TEACHER".to_string()]),
+            current_department_id: None,
     };
     jwt_encode_token(token).expect("encode test token")
 }