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/config/mail.php

@@ -0,0 +1,118 @@
+<?php
+
+return [
+
+    /*
+    |--------------------------------------------------------------------------
+    | Default Mailer
+    |--------------------------------------------------------------------------
+    |
+    | This option controls the default mailer that is used to send all email
+    | messages unless another mailer is explicitly specified when sending
+    | the message. All additional mailers can be configured within the
+    | "mailers" array. Examples of each type of mailer are provided.
+    |
+    */
+
+    'default' => env('MAIL_MAILER', 'log'),
+
+    /*
+    |--------------------------------------------------------------------------
+    | Mailer Configurations
+    |--------------------------------------------------------------------------
+    |
+    | Here you may configure all of the mailers used by your application plus
+    | their respective settings. Several examples have been configured for
+    | you and you are free to add your own as your application requires.
+    |
+    | Laravel supports a variety of mail "transport" drivers that can be used
+    | when delivering an email. You may specify which one you're using for
+    | your mailers below. You may also add additional mailers if needed.
+    |
+    | Supported: "smtp", "sendmail", "mailgun", "ses", "ses-v2",
+    |            "postmark", "resend", "log", "array",
+    |            "failover", "roundrobin"
+    |
+    */
+
+    'mailers' => [
+
+        'smtp' => [
+            'transport' => 'smtp',
+            'scheme' => env('MAIL_SCHEME'),
+            'url' => env('MAIL_URL'),
+            'host' => env('MAIL_HOST', '127.0.0.1'),
+            'port' => env('MAIL_PORT', 2525),
+            'username' => env('MAIL_USERNAME'),
+            'password' => env('MAIL_PASSWORD'),
+            'timeout' => null,
+            'local_domain' => env('MAIL_EHLO_DOMAIN', parse_url((string) env('APP_URL', 'http://localhost'), PHP_URL_HOST)),
+        ],
+
+        'ses' => [
+            'transport' => 'ses',
+        ],
+
+        'postmark' => [
+            'transport' => 'postmark',
+            // 'message_stream_id' => env('POSTMARK_MESSAGE_STREAM_ID'),
+            // 'client' => [
+            //     'timeout' => 5,
+            // ],
+        ],
+
+        'resend' => [
+            'transport' => 'resend',
+        ],
+
+        'sendmail' => [
+            'transport' => 'sendmail',
+            'path' => env('MAIL_SENDMAIL_PATH', '/usr/sbin/sendmail -bs -i'),
+        ],
+
+        'log' => [
+            'transport' => 'log',
+            'channel' => env('MAIL_LOG_CHANNEL'),
+        ],
+
+        'array' => [
+            'transport' => 'array',
+        ],
+
+        'failover' => [
+            'transport' => 'failover',
+            'mailers' => [
+                'smtp',
+                'log',
+            ],
+            'retry_after' => 60,
+        ],
+
+        'roundrobin' => [
+            'transport' => 'roundrobin',
+            'mailers' => [
+                'ses',
+                'postmark',
+            ],
+            'retry_after' => 60,
+        ],
+
+    ],
+
+    /*
+    |--------------------------------------------------------------------------
+    | Global "From" Address
+    |--------------------------------------------------------------------------
+    |
+    | You may wish for all emails sent by your application to be sent from
+    | the same address. Here you may specify a name and address that is
+    | used globally for all emails that are sent by your application.
+    |
+    */
+
+    'from' => [
+        'address' => env('MAIL_FROM_ADDRESS', 'hello@example.com'),
+        'name' => env('MAIL_FROM_NAME', env('APP_NAME', 'Laravel')),
+    ],
+
+];