Fix 40+ codebase issues: security, performance, duplication, dead code, and routes

HIGH:
- Add missing import RadioSongRequestFormRequest (fixes crash on POST)
- Add Purify XSS sanitization for article full_story
- Fix duplicate radio API routes (/api/radio vs /api/radio/v2)
- Add try-catch guards in InstallationController for missing records

MEDIUM:
- Fix N+1: eager load comments.user in ArticleController::show()
- Fix GuestbookController authorization logic
- Remove dead doSetup() method and duplicate route
- Extract shared HasRadioDefaults trait (remove code duplication)
- Use named routes in ForceStaffTwoFactorMiddleware
- Fix WebsiteHelpCenterTicket::isOpen() (no permission leak)
- Enable  on WebsiteHelpCenterTicket (matches schema)
- Replace WebsiteTeam::all()->pluck() with direct pluck()
- Replace CatalogPage::all()->pluck() with direct pluck()
- Replace WebsiteBadge::all() with direct pluck()
- Add throttle middleware to guestbook store, logo-generator, radio embed

LOW:
- Remove unused imports
- Remove dead /inertia-test route
- Consolidate cache keys in RadioController

app/Http/Controllers/Community/RadioController.php

@@ -164,6 +164,7 @@ class RadioController extends Controller
         ]);
 
         Cache::forget('radio_shouts_recent');
+        Cache::forget('api_radio_shouts');
 
         return redirect()->route('radio.shouts')->with('success', __('radio.shout_sent'));
     }
@@ -308,7 +309,7 @@ class RadioController extends Controller
             return response()->json(['error' => 'Shouts zijn uitgeschakeld', 'shouts' => []], 403);
         }
 
-        $shouts = Cache::remember('radio_shouts_recent', 30, fn () => RadioShout::with('user:id,username')
+        $shouts = Cache::remember('api_radio_shouts', 30, fn () => RadioShout::with('user:id,username')
             ->orderBy('created_at', 'desc')
             ->take(50)
             ->get()