feat(admin): rebuild release upload form with Livewire and CDN validation

Replace the server-rendered release upload form with a Livewire component,
introducing an interactive admin release form that supports dynamic episode
management, real‑time CDN path validation, and direct download file checks.

Key changes:
- New `AdminReleaseForm` Livewire component with dynamic episode fields,
  Tagify integration, and upload handling via Livewire's file uploads.
- Added `CdnPathValidator` service to verify download and stream paths across
  all configured mirrors, caching results and capturing file sizes.
- Extended `EpisodeService` and `GalleryService` to support array‑based data
  and temporary uploaded files from Livewire.
- Persist validated download sizes and store the validation timestamp on the
  `downloads` table via a new migration; also add a unique constraint on
  `hentais.slug` to prevent duplicates.
- Remove the old POST `/admin/release/upload` route and controller logic,
  along with the legacy `upload.js` script.
- Add comprehensive feature and unit tests covering the new component and the
  CDN validation service.

routes/admin.php

@@ -41,11 +41,9 @@ Route::group(['middleware' => ['auth', 'auth.admin']], function () {
 
     // Release
     Route::get('/admin/release', [ReleaseController::class, 'index'])->name('admin.upload.index');
-    Route::post('/admin/release/upload', [ReleaseController::class, 'store'])->name('admin.upload');
 
     // Episode
     Route::post('/admin/episode/upload', [EpisodeController::class, 'store'])->name('admin.upload.episode');
-    
 
     // Get Tags used for Upload Form
     Route::get('/admin/tags', [AdminApiController::class, 'getTags'])->name('admin.tags');
@@ -69,4 +67,4 @@ Route::group(['middleware' => ['auth', 'auth.moderator']], function () {
 
     // Edit Episode
     Route::post('/admin/episode/edit', [EpisodeController::class, 'update'])->name('admin.episode.edit');
-});
+});