feat(search): /search?q= across videos, channels and playlists

Add a dedicated SearchController that matches the query against video
title / description / tags / primary language AND any secondary audio
track language (so "arabic" surfaces videos that carry an Arabic track
even if the primary language is English), plus channel name / username
/ bio, plus playlist name / description. Public visibility only.

Results reuse the videos/index view so every card gets the same
component the browse feeds use. A new Channels section renders above
the Videos grid when channel hits exist.

/videos/search is kept as a 301 redirect to /search so bookmarks and
external links stay valid; both the desktop header and mobile overlay
search forms now point at the canonical route, both carry a visually
hidden <label>, both get role="search" and both preserve the current
query in their input.

Co-Authored-By: Claude Opus 4.7 (1M context) <[email protected]>

routes/web.php

@@ -25,7 +25,13 @@ Route::get('/', [VideoController::class, 'index'])->name('home');
 // Video routes - public
 Route::get('/videos', [VideoController::class, 'index'])->name('videos.index');
 Route::get('/videos/feed/more', [VideoController::class, 'feedMore'])->name('videos.feed.more');
-Route::get('/videos/search', [VideoController::class, 'search'])->name('videos.search');
+
+// Site-wide search. /videos/search is the historical URL; keep it as a
+// signed-forward redirect so bookmarks and external links don't break.
+Route::get('/search', [\App\Http\Controllers\SearchController::class, 'index'])->name('search');
+Route::get('/videos/search', function (\Illuminate\Http\Request $request) {
+    return redirect()->route('search', $request->only('q'), 301);
+})->name('videos.search');
 Route::get('/trending', [VideoController::class, 'trending'])->name('videos.trending');
 Route::get('/shorts', [VideoController::class, 'shorts'])->name('videos.shorts');
 Route::get('/videos/create', [VideoController::class, 'create'])->name('videos.create');