Remove PostHog analytics and update dependencies to latest minor versions

- Remove posthog-js and posthog-node dependencies
- Delete PostHogProvider component and lib/posthog.ts
- Remove PostHog configuration from environment files
- Remove PostHog rewrites from next.config.mjs
- Update all npm subdependencies to latest minor versions
- Update @types/react and @types/react-dom overrides to 19.2.9 and 19.2.3

lib/navidrome.ts

@@ -1,5 +1,4 @@
 import crypto from 'crypto';
-import { albumCache, artistCache, songCache, imageCache, PersistentCache } from './cache';
 
 export interface NavidromeConfig {
   serverUrl: string;