fix: resolve CVEs, upgrade to Astro v6, and harden API security (#227)

* fix: resolve CVEs, upgrade to Astro v6, and harden API security

Docker image CVE fixes:
- Install git-lfs v3.7.1 from GitHub releases (Go 1.25) instead of
  Debian apt (Go 1.23.12), fixing CVE-2025-68121 and 8 other Go stdlib CVEs
- Strip build-only packages (esbuild, vite, rollup, svgo, tailwindcss)
  from production image, eliminating 9 esbuild Go stdlib CVEs

Dependency upgrades:
- Astro v5 → v6 (includes Vite 7, Zod 4)
- Remove legacy content config (src/content/config.ts)
- Update HealthResponse type for simplified health endpoint
- npm overrides for fast-xml-parser ≥5.3.6, devalue ≥5.6.2,
  node-forge ≥1.3.2, svgo ≥4.0.1, rollup ≥4.59.0

API security hardening:
- /api/auth/debug: dev-only, require auth, remove user-creation POST,
  strip trustedOrigins/databaseConfig from response
- /api/auth/check-users: return boolean hasUsers instead of exact count
- /api/cleanup/auto: require authentication, remove per-user details
- /api/health: remove OS version, memory, uptime from response
- /api/config: validate Gitea URL protocol (http/https only)
- BETTER_AUTH_SECRET: log security warning when using insecure defaults
- generateRandomString: replace Math.random() with crypto.getRandomValues()
- hashValue: add random salt and timing-safe verification

* repositories: migrate table to tanstack

* Revert "repositories: migrate table to tanstack"

This reverts commit a544b29e6d.

* fixed lock file

src/lib/utils.ts

@@ -11,9 +11,11 @@ export function cn(...inputs: ClassValue[]) {
 
 export function generateRandomString(length: number): string {
   const chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789';
+  const randomValues = new Uint32Array(length);
+  crypto.getRandomValues(randomValues);
   let result = '';
   for (let i = 0; i < length; i++) {
-    result += chars.charAt(Math.floor(Math.random() * chars.length));
+    result += chars.charAt(randomValues[i] % chars.length);
   }
   return result;
 }