Fix iOS text color, viewport meta tag, and security improvements

- Add viewport meta tag to prevent iOS zoom/scaling issues
- Fix text color on iOS Safari (explicit text-gray-900 on buttons, inputs, TimePicker5)
- Add session checks to /api/beos, /api/objekte, /api/wetter
- Revert iframe embedding (X-Frame-Options: DENY, SameSite: lax)
- docker-compose.prod.yml: fix DB_PORT=3306 for production
- Add docker-compose.prod.yml, .env.prod.example, dump/import scripts

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

components/TimePicker5.tsx

@@ -58,7 +58,7 @@ export default function TimePicker5({ value, onChange, className = '' }: Props)
       }}
       className={`flex items-center border-2 border-gray-400 rounded-lg bg-white focus:border-blue-500 focus:outline-none select-none ${className}`}
     >
-      <span className="flex-1 px-3 py-2 text-sm font-mono text-center">{value}</span>
+      <span className="flex-1 px-3 py-2 text-sm font-mono text-center text-gray-900">{value}</span>
       <div className="flex flex-col border-l border-gray-300 shrink-0">
         <button {...buttonProps(5)}  className="px-2 pt-1 pb-0.5 hover:bg-gray-100 text-gray-500 text-xs leading-none">▲</button>
         <button {...buttonProps(-5)} className="px-2 pt-0.5 pb-1 hover:bg-gray-100 text-gray-500 text-xs leading-none">▼</button>