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/resources/views/overlays/landing.blade.php

@@ -0,0 +1,163 @@
+@extends('layouts.overlay')
+
+@section('title', 'STAND BY')
+
+@section('styles')
+<style>
+  body.overlay-body {
+    display: grid;
+    grid-template-rows: auto 1fr auto auto;
+    gap: 24px;
+  }
+  .stage {
+    display: flex;
+    flex-direction: column;
+    align-items: center;
+    justify-content: center;
+    gap: 36px;
+  }
+  .mark {
+    width: 360px; height: 360px;
+    filter: drop-shadow(0 0 22px rgba(58, 209, 255, 0.35));
+  }
+  .bars {
+    display: flex;
+    width: 720px;
+    height: 14px;
+    opacity: 0.32;
+  }
+  .bars i { flex: 1; display: block; }
+  .bars i:nth-child(1) { background: #c7c7c7; }
+  .bars i:nth-child(2) { background: #c7c700; }
+  .bars i:nth-child(3) { background: #00c7c7; }
+  .bars i:nth-child(4) { background: #00c700; }
+  .bars i:nth-child(5) { background: #c700c7; }
+  .bars i:nth-child(6) { background: #c70000; }
+  .bars i:nth-child(7) { background: #0000c7; }
+</style>
+@endsection
+
+@push('data-scripts')
+<script>window.__TEL = @json($telemetry);</script>
+@endpush
+
+@section('content')
+  @include('partials.hud-strip', [
+    'variant' => 'live',
+    'label'   => 'TRANSMISSION',
+    'extraIdSlot' => '<span class="station"><span class="station-id">OPHI-118</span><span class="sep">//</span><span class="rig" id="rigName">--</span></span>',
+  ])
+
+  <main class="stage">
+    <svg class="mark" viewBox="0 0 200 200" xmlns="http://www.w3.org/2000/svg">
+      <circle cx="100" cy="100" r="92" fill="none" stroke="#3ad1ff" stroke-width="1.2" opacity="0.35"/>
+      <circle cx="100" cy="100" r="80" fill="none" stroke="#3ad1ff" stroke-width="2.5"/>
+      <g stroke="#3ad1ff" stroke-width="2" opacity="0.55">
+        <line x1="100" y1="8"   x2="100" y2="22"/>
+        <line x1="100" y1="178" x2="100" y2="192"/>
+        <line x1="8"   y1="100" x2="22"  y2="100"/>
+        <line x1="178" y1="100" x2="192" y2="100"/>
+      </g>
+      <polygon points="100,52 148,140 52,140"
+               fill="none" stroke="#e63a2e" stroke-width="3.5" stroke-linejoin="miter"/>
+      <circle cx="100" cy="116" r="4" fill="#ffd000"/>
+    </svg>
+    <div class="bars"><i></i><i></i><i></i><i></i><i></i><i></i><i></i></div>
+  </main>
+
+  <section class="standby">
+    <div class="big">PLEASE STAND BY</div>
+    <div class="sub">&mdash; DO NOT ADJUST YOUR RECEIVER &mdash;</div>
+  </section>
+
+  <footer class="foot">
+    <span>CH 118.0 MHz</span>
+    <span id="rig">&mdash; TELEMETRY &mdash;</span>
+    <span class="warn">&#x25B2; AUDIO ACTIVE</span>
+  </footer>
+@endsection
+
+@section('scripts')
+<script>
+  'use strict';
+  const rigNameEl = document.getElementById('rigName');
+  const RIG_NAME = (window.__TEL && window.__TEL.rig) || 'UNKNOWN';
+  const upperRig = String(RIG_NAME).toUpperCase();
+  const scrambleRig = ({ initial = false } = {}) => {
+    if (!upperRig.length) { rigNameEl.textContent = '--'; return; }
+    HUD.scrambleReveal(rigNameEl, upperRig, {
+      scrambleMs: initial ? 600 : 360, stepMs: 50, resolveStepMs: 60,
+    });
+  };
+  setTimeout(() => scrambleRig({ initial: true }), 600);
+  setInterval(scrambleRig, 9000);
+
+  // Rotating telemetry footer.
+  const rigEl = document.getElementById('rig');
+  const tel = window.__TEL || null;
+  const shortCpu = (m) => (m || '')
+    .replace(/\(R\)|\(TM\)/g, '')
+    .replace(/\s+\S+-Core\s+Processor\b/i, '')
+    .replace(/\s+Processor\b/i, '')
+    .replace(/\s+CPU\b.*$/i, '')
+    .replace(/\s+@.*$/, '')
+    .replace(/\s+/g, ' ')
+    .trim();
+  const lines = [
+    () => {
+      if (!tel?.cpu?.model) return null;
+      let s = `CPU · ${shortCpu(tel.cpu.model)}`;
+      if (tel.cpu.threads) s += ` · ${tel.cpu.threads}T`;
+      if (tel.mem?.totalGB) s += `  ·  MEM ${tel.mem.totalGB} GB`;
+      return s;
+    },
+    () => {
+      if (!tel?.gpu?.name) return null;
+      let s = `GPU · ${tel.gpu.name}`;
+      if (tel.gpu.vramTotalMB) s += ` · ${(tel.gpu.vramTotalMB / 1024).toFixed(0)} GB VRAM`;
+      return s;
+    },
+    () => {
+      const o = tel?.obs;
+      if (!o?.output?.w) return null;
+      let s = `OUTPUT · ${o.output.w}×${o.output.h}`;
+      if (o.fps) s += ` @ ${o.fps} FPS`;
+      if (o.stream?.encoder) s += ` · ${o.stream.encoder}`;
+      return s;
+    },
+    () => {
+      const s = tel?.obs?.stream;
+      if (!s) return null;
+      const parts = [];
+      if (s.rateControl) parts.push(s.rateControl);
+      if (s.bitrateKbps) parts.push(`${s.bitrateKbps} kbps`);
+      if (s.profile)     parts.push(s.profile.toUpperCase());
+      return parts.length ? `STREAM · ${parts.join(' · ')}` : null;
+    },
+    () => tel?.host?.kernel ? `KERNEL · ${tel.host.kernel}` : null,
+  ];
+  let lineIdx = 0;
+  const nextLine = () => {
+    for (let i = 0; i < lines.length; i++) {
+      const v = lines[lineIdx]();
+      if (v) return v;
+      lineIdx = (lineIdx + 1) % lines.length;
+    }
+    return '— TELEMETRY OFFLINE —';
+  };
+  rigEl.textContent = nextLine();
+  const swapLine = () => {
+    const text = nextLine();
+    const len = Math.max(text.length, 1);
+    HUD.scrambleReveal(rigEl, text, {
+      scrambleMs: 280,
+      stepMs: 45,
+      resolveStepMs: Math.max(15, Math.floor(700 / len)),
+    });
+  };
+  setInterval(() => {
+    lineIdx = (lineIdx + 1) % lines.length;
+    swapLine();
+  }, 6000);
+</script>
+@endsection