feat: migrate frontend to Astro + expand AI moderation + backend admin/runtime config

Frontend:
- migrate from Vite to Astro (astro.config.mjs, pages/, layouts/)
- add admin panel, settings page, command palette, error boundary
- refactor App.tsx, MascotChatbot, Sidebar, Header, DashboardLayout
- update API client, WebSocket, auth, dashboard features

Backend:
- add admin module and config routes
- refactor middlewares, Redis connection, WebSocket server/bridge
- add runtime config loader

Discord Gateway:
- refactor AI moderation: circuit breaker, concurrency limiter, fallback processor
- add media analysis client, Seaxng search, user profile learner
- add new drizzle migration

Shared:
- extend database schema, add new config fields

services/backend/src/modules/dashboard/dashboard.routes.ts

@@ -23,7 +23,7 @@ export function createDashboardRouter(): Router {
   router.get(
     "/dashboard/users",
     asyncHandler(async (req: Request, res: Response) => {
-      const limit = Number(req.query.limit) || 20;
+      const limit = Math.min(Number(req.query.limit) || 20, 100);
       const cursor =
         typeof req.query.cursor === "string" ? req.query.cursor : undefined;
       const search =
@@ -52,16 +52,19 @@ export function createDashboardRouter(): Router {
   router.get(
     "/dashboard/channels",
     asyncHandler(async (req: Request, res: Response) => {
-      const limit = Number(req.query.limit) || 20;
+      const limit = Math.min(Number(req.query.limit) || 20, 100);
       const search =
         typeof req.query.search === "string" ? req.query.search : undefined;
       const guildId =
         typeof req.query.guild_id === "string" ? req.query.guild_id : undefined;
+      const cursor =
+        typeof req.query.cursor === "string" ? req.query.cursor : undefined;
 
       const result = await dashboardService.listChannels({
         limit,
         search,
         guildId,
+        cursor,
       });
       res.json(result);
     }),