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/CustomSelect.tsx

@@ -39,7 +39,7 @@ export default function CustomSelect({ options, placeholder, onChange, keepOpen
       <button
         type="button"
         onClick={() => setOpen((v) => !v)}
-        className="w-full flex items-center justify-between px-4 py-2 border-2 border-gray-400 rounded-lg bg-white text-base text-gray-700 focus:border-blue-500 focus:outline-none"
+        className="w-full flex items-center justify-between px-4 py-2 border-2 border-gray-400 rounded-lg bg-white text-base text-gray-900 focus:border-blue-500 focus:outline-none"
       >
         <span>{placeholder}</span>
         <svg
@@ -58,7 +58,7 @@ export default function CustomSelect({ options, placeholder, onChange, keepOpen
               type="button"
               disabled={opt.disabled}
               onClick={() => select(opt.value)}
-              className="w-full text-left px-4 py-2 text-base hover:bg-blue-50 active:bg-blue-100 border-b border-gray-100 last:border-0 disabled:text-gray-400 disabled:bg-gray-50"
+              className="w-full text-left px-4 py-2 text-base text-gray-900 hover:bg-blue-50 active:bg-blue-100 border-b border-gray-100 last:border-0 disabled:text-gray-400 disabled:bg-gray-50"
             >
               {opt.label}
             </button>