feat: migrate Leptos frontend to Next.js 16 (React 19)

Complete migration from services/frontend.old/ (Leptos 0.7 WASM + Rust)
to services/frontend/ (Next.js 16 static export + TypeScript + Tailwind v4).

Summary:
- Port all shared types (message, guild, voice, media, dashboard, recording, ui)
- Build fetch-based API client covering all 30+ backend endpoints
- WebSocket client with auto-reconnect (exponential backoff, 20 attempts)
- React context provider for WS with typed event subscription (22 event types)
- Login page with localStorage auth + auto-redirect
- Dashboard layout with sidebar, header (WS status + theme toggle)
- Messages: feed, search, images tab, review tab, channel filter, detail modal
- Live: voice connection, music player, recordings, mic transmit, active speakers
- Dashboard: stats, user list, channel list, detail views
- Mascot chatbot with history + clear
- uiStateApi persistence for selected tab
- Add static export config, update deploy scripts and CI

services/frontend/src/lib/api/recordings.ts

@@ -0,0 +1,21 @@
+import type { PaginatedRecordings } from "@/lib/types";
+import { api } from "./client";
+
+export const recordingsApi = {
+  list: (
+    limit?: number,
+    channelId?: string,
+    userId?: string,
+    cursor?: string,
+  ) => {
+    const params = new URLSearchParams();
+    if (limit) params.set("limit", String(limit));
+    if (channelId) params.set("channelId", channelId);
+    if (userId) params.set("userId", userId);
+    if (cursor) params.set("cursor", cursor);
+    const qs = params.toString();
+    return api.get<PaginatedRecordings>(`/api/recordings${qs ? `?${qs}` : ""}`);
+  },
+
+  delete: (id: string) => api.delete<{ ok: boolean }>(`/api/recordings/${id}`),
+};