feat: modularize scanner, enhance carousel preloading, and improve PWA updates

Summary of changes:
- Extracted archive scanning logic into a modular 'useArchiveScanner' hook for better maintainability and performance.
- Refined PostModal carousel with intelligent media preloading and smoother, jitter-free transitions.
- Optimized image rendering with 'decoding=async' and removed 'black flashes' between slide changes.
- Updated PWA configuration to 'autoUpdate' with hourly periodic checks for fresh content.
- Fixed several bugs including stories sorting, permalink parameter cleanup, and profile metadata cache restoration.
- Comprehensive updates to documentation (README.md and GEMINI.md) reflecting the new architecture.

src/lib/utils.ts

@@ -0,0 +1,6 @@
+import { clsx, type ClassValue } from 'clsx';
+import { twMerge } from 'tailwind-merge';
+
+export function cn(...inputs: ClassValue[]) {
+  return twMerge(clsx(inputs));
+}