feat: audit log time-range filter + script execution schedules

Audit log time-range filter:
- audit_log_repo.py: unified query() with action/admin_username/date_from/date_to
  filters + total count; _build_filters() helper for date parsing
- settings.py GET /audit/: add date_from, date_to, admin_username query params
- audit.html: date range inputs (YYYY-MM-DD), admin filter input, action filter
  expanded with optgroups (服务器/推送/脚本/认证/设置); clear filter button

Script execution schedules:
- domain/models: PushSchedule extended with schedule_type('push'|'script'),
  script_id FK, script_content Text, exec_timeout int, long_task bool;
  source_path made nullable
- migrations.py: 6 new ALTER TABLE statements (idempotent)
- schedule_runner.py: detect schedule_type; for 'script' type use ScriptService;
  for 'push' type keep original SyncEngineV2 sync_files behaviour
- schemas.py: ScheduleCreate/Update add all new fields
- schedules.html: full UI rewrite
  - type selector radio: 📁 文件推送 / ⚡ 脚本执行
  - script fields: script library dropdown + textarea + timeout + long_task
  - schedule list shows type badge + detail preview
  - saveSched() validates required fields per type

Co-authored-by: Cursor <cursoragent@cursor.com>

server/api/settings.py

@@ -288,18 +288,24 @@ audit_router = APIRouter(prefix="/api/audit", tags=["audit"])
 @audit_router.get("/", response_model=dict)
 async def list_audit_logs(
     action: Optional[str] = None,
+    admin_username: Optional[str] = None,
+    date_from: Optional[str] = None,   # ISO date: YYYY-MM-DD or YYYY-MM-DDTHH:MM:SS
+    date_to: Optional[str] = None,
     limit: int = 50,
     offset: int = 0,
     admin: Admin = Depends(get_current_admin),
     db: AsyncSession = Depends(get_db),
 ):
-    """List audit logs with pagination"""
+    """List audit logs with pagination, action filter, admin filter, and date range."""
     repo = AuditLogRepositoryImpl(db)
-    total = await repo.count(action)
-    if action:
-        logs = await repo.get_by_action(action, limit, offset)
-    else:
-        logs = await repo.get_recent(limit, offset)
+    logs, total = await repo.query(
+        action=action,
+        admin_username=admin_username,
+        date_from=date_from,
+        date_to=date_to,
+        limit=limit,
+        offset=offset,
+    )
     return {
         "total": total,
         "limit": limit,