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/discord-gateway/src/modules/ai-moderation/concurrencyLimiter.ts

@@ -22,7 +22,6 @@ function updateCounts(): void {
 }
 
 export async function withLlmConcurrency<T>(fn: () => Promise<T>): Promise<T> {
-  const queuedAt = activeCount + pendingCount;
   pendingCount++;
   logger.debug(
     { activeCount, pendingCount, maxConcurrent: config.AI_LLM_MAX_CONCURRENT },
@@ -30,17 +29,17 @@ export async function withLlmConcurrency<T>(fn: () => Promise<T>): Promise<T> {
   );
 
   return llmSemaphore(async () => {
-    pendingCount--;
-    activeCount++;
-
-    if (activeCount >= (config.AI_LLM_MAX_CONCURRENT ?? 5)) {
-      logger.warn(
-        { activeCount, maxConcurrent: config.AI_LLM_MAX_CONCURRENT },
-        "LLM concurrency limit reached",
-      );
-    }
-
     try {
+      pendingCount--;
+      activeCount++;
+
+      if (activeCount >= (config.AI_LLM_MAX_CONCURRENT ?? 5)) {
+        logger.warn(
+          { activeCount, maxConcurrent: config.AI_LLM_MAX_CONCURRENT },
+          "LLM concurrency limit reached",
+        );
+      }
+
       return await fn();
     } finally {
       activeCount--;