feat(security): enhance security policies and implement input validation across multiple files

.htaccess

@@ -12,8 +12,14 @@ Header always set Referrer-Policy "strict-origin-when-cross-origin"
 Header always set Permissions-Policy "geolocation=(), microphone=(), camera=()"
 Header always set Cross-Origin-Opener-Policy "same-origin"
 Header always set Cross-Origin-Embedder-Policy "require-corp"
+Header always set Content-Security-Policy "default-src 'self'; script-src 'self' 'wasm-unsafe-eval' 'unsafe-eval' blob: https://cdn.jsdelivr.net; worker-src 'self' blob:; style-src 'self' 'unsafe-inline' https://fonts.googleapis.com; img-src 'self' data: blob: https:; font-src 'self' data: https://fonts.gstatic.com https://rawcdn.githack.com; connect-src 'self' blob: https://api.github.com https://fonts.gstatic.com https://cdn.jsdelivr.net https://bentopdf-cors-proxy.bentopdf.workers.dev https://rawcdn.githack.com; object-src 'none'; base-uri 'self'; frame-src 'self' blob:; frame-ancestors 'self'; form-action 'self'"
 </IfModule>
 
+# Block source maps from being served
+<FilesMatch "\.map$">
+  Require all denied
+</FilesMatch>
+
 # ============================================
 # 2. BROWSER CACHING
 # ============================================