webapp: introduce Laravel app under webapp/ for scene overlays

Replaces the per-scene HTML directories (landing/, loading/, game/,
desktop/, goodbye/, music-box/, music/) with a single Laravel app
serving every overlay over HTTP. Supervisord runs `php artisan serve`
on 127.0.0.1:1118 and the OBS scene JSON now references HTTP routes
instead of file:// URLs.

Highlights:
 - public/css/hud.css consolidates the duplicated HUD chrome,
   scanlines/vignette/flicker, terminal styling, and pulse keyframes
   that were copy-pasted across all seven scenes.
 - Blade partials own hud-strip, crt-overlays, obs-ws-scripts,
   camera-frame, screen-frame; the seven scenes extend a shared
   overlay layout.
 - Artisan commands (`rig:setup`, `rig:telemetry`, `rig:loading`,
   `rig:playlist`, `rig:cmd`) replace the shell scripts that wrote
   per-rig JSON snapshots. TwitchHelix + HardwareSnapshot services
   handle the work the bash + Python helpers used to.
 - ObsWsClient + MusicCommandController kill the 250 ms cmd.js poll
   in the music daemon: POST /cmd/{skip|prev|pause|resume} opens a
   short-lived Pawl WS, authenticates, and broadcasts mpd:cmd.
 - AudioController streams files from the configured music dirs so
   CEF can load tracks under the HTTP origin (Chromium blocks
   HTTP-origin pages from loading file:// media).
 - DataController serves /data/playlist.js (with ETag mtime cache)
   and /cover.jpg (no-store) so the existing overlays' window.__PLAYLIST
   and cover.jpg cache-bust pattern keeps working.

scripts/obs-webapp.supervisord.conf is the supervisord unit; install
to /etc/supervisor.d/obs-webapp.conf.
scripts/rewrite-scene-urls.py is a one-shot tool that rewrites
basic/scenes/Default_Stream_HUD.json from file:// to HTTP URLs.
basic/scenes/Default_Stream_HUD.json.pre-webapp is the rollback
artifact (made with OBS closed; full pre-migration state).

The seven old scene directories, vendor/, and the bash scripts are
still on disk pending visual verification; the next commit will
prune them.

webapp/app/Console/Commands/RigLoadingCommand.php

@@ -0,0 +1,101 @@
+<?php
+
+namespace App\Console\Commands;
+
+use App\Services\TwitchHelix;
+use App\Support\RigData;
+use Illuminate\Console\Command;
+use Throwable;
+
+class RigLoadingCommand extends Command
+{
+    protected $signature = 'rig:loading {--no-twitch : Skip pushing the channel update to Twitch}';
+    protected $description = 'Interactive Project Loading manifest builder';
+
+    public function handle(RigData $rig, TwitchHelix $twitch): int
+    {
+        $prev = $rig->loading();
+
+        $this->line('── Project Loading manifest ──');
+        $this->line('  (press Enter to keep [defaults])');
+        $this->line('');
+
+        $game = null;
+        $gameId = null;
+        $defaultGame = (string) ($prev['game'] ?? '');
+        while (true) {
+            $query = (string) $this->ask('Game (search)', $defaultGame ?: null);
+            if ($query === '') {
+                $this->error('  ✗ Game is required');
+                continue;
+            }
+            if ($twitch->enabled()) {
+                $cachedId = (string) ($prev['gameId'] ?? '');
+                if ($query === $defaultGame && preg_match('/^\d+$/', $cachedId)) {
+                    $game = $defaultGame;
+                    $gameId = $cachedId;
+                    $this->line("  ↻ reusing cached: {$game} (id={$gameId})");
+                    break;
+                }
+                try {
+                    $hit = $twitch->searchCategory($query);
+                } catch (Throwable $e) {
+                    $this->warn('  ! Twitch search failed: ' . $e->getMessage());
+                    if ($this->confirm('Use the raw input without resolving an id?', true)) {
+                        $game = $query;
+                        break;
+                    }
+                    continue;
+                }
+                if ($hit === null) {
+                    $this->warn('  ! no Twitch matches for "' . $query . '"');
+                    continue;
+                }
+                $game = $hit['name'];
+                $gameId = $hit['id'];
+                $this->line("  ↳ matched: {$game} (id={$gameId})");
+                break;
+            }
+            $game = $query;
+            break;
+        }
+
+        $subtitle    = (string) $this->ask('Subtitle (mode / episode / note)', $prev['subtitle'] ?? null);
+        $countdown   = (int)    $this->ask('Countdown (minutes)', (string) ($prev['countdownMin'] ?? 5));
+        $camera      = $this->confirm('Camera', (bool) ($prev['camera']     ?? true));
+        $microphone  = $this->confirm('Microphone', (bool) ($prev['microphone'] ?? true));
+
+        $data = [
+            'compiledAt'   => gmdate('Y-m-d\TH:i:s\Z'),
+            'game'         => $game,
+            'gameId'       => $gameId,
+            'subtitle'     => $subtitle ?: null,
+            'countdownMin' => $countdown,
+            'camera'       => $camera,
+            'microphone'   => $microphone,
+        ];
+        $path = rtrim(config('rig.storage_data'), '/') . '/loading.json';
+        @mkdir(dirname($path), 0775, true);
+        file_put_contents(
+            $path,
+            json_encode($data, JSON_PRETTY_PRINT | JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE) . "\n"
+        );
+        $this->info('');
+        $this->info("  ✓ wrote {$path}");
+
+        // Push to Twitch — soft-fail so a network blip doesn't block the local manifest.
+        if (!$this->option('no-twitch') && $twitch->enabled() && $gameId) {
+            $title = $subtitle ?: $game;
+            try {
+                $twitch->setChannel($title, $gameId);
+                $this->info("  ✓ Twitch channel updated → \"{$title}\" / category {$game}");
+            } catch (Throwable $e) {
+                $this->warn('  ! Twitch sync failed (manifest still saved): ' . $e->getMessage());
+            }
+        }
+
+        $this->line('');
+        $this->line('  → refresh the Project Loading browser source in OBS.');
+        return self::SUCCESS;
+    }
+}