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/public/js/hud.js

@@ -0,0 +1,106 @@
+/* OPHI-118 — shared HUD helpers used by every overlay.
+ *
+ * Exposes:
+ *   - HUD.startClock(el)       — UTC ticker into the given element.
+ *   - HUD.startSignal(el, opts) — signal-bar fluctuator.
+ *   - HUD.scrambleReveal(...)  — cyberpunk decode/scramble used by landing.
+ *
+ * Designed to no-op if the target element isn't on the page, so the
+ * base layout can include it unconditionally.
+ */
+(function (root) {
+  'use strict';
+
+  const pad = n => String(n).padStart(2, '0');
+
+  function startClock(el) {
+    if (!el) return;
+    const tick = () => {
+      const d = new Date();
+      el.textContent =
+        `${pad(d.getUTCHours())}:${pad(d.getUTCMinutes())}:${pad(d.getUTCSeconds())}`;
+    };
+    tick();
+    setInterval(tick, 1000);
+  }
+
+  // n thresholds default to the original landing/loading/game distribution:
+  //   r < .06 → 2 bars  (occasional drop)
+  //   r < .70 → 3 bars  (typical)
+  //   r < .95 → 4 bars
+  //          → 5 bars  (occasional spike)
+  function startSignal(el, opts) {
+    if (!el) return;
+    const profile = opts?.profile || 'normal';
+    const FILL = '▮', EMPTY = '▯';
+    const draw = n => FILL.repeat(n) + EMPTY.repeat(5 - n);
+    setInterval(() => {
+      const r = Math.random();
+      let n;
+      if (profile === 'strong') {
+        n = r < 0.15 ? 3 : r < 0.65 ? 4 : 5;
+      } else if (profile === 'degrading') {
+        n = r < 0.45 ? 1 : r < 0.85 ? 2 : r < 0.97 ? 3 : 0;
+      } else {
+        n = r < 0.06 ? 2 : r < 0.70 ? 3 : r < 0.95 ? 4 : 5;
+      }
+      el.textContent = draw(n);
+    }, 1500);
+  }
+
+  // ASCII-only glyph pool — DejaVu Mono renders these at 1ch each, so the
+  // intermediate frames don't shift width.
+  const GLITCH_GLYPHS = '01ABCDEFGHIJKLMNOPQRSTUVWXYZ#@*?!§%';
+  const glyph = () => GLITCH_GLYPHS[(Math.random() * GLITCH_GLYPHS.length) | 0];
+  const _scrambleHandles = new WeakMap();
+
+  function scrambleReveal(el, finalText, opts) {
+    opts = opts || {};
+    const { scrambleMs = 360, stepMs = 50, resolveStepMs = 60 } = opts;
+    const prev = _scrambleHandles.get(el);
+    if (prev) { clearInterval(prev.s); clearInterval(prev.r); }
+    const len = finalText.length;
+    if (!len) {
+      el.textContent = '';
+      el.classList.remove('glitching');
+      _scrambleHandles.delete(el);
+      return;
+    }
+    el.classList.add('glitching');
+    const scrambleSteps = Math.max(1, Math.floor(scrambleMs / stepMs));
+    const handle = { s: null, r: null };
+    _scrambleHandles.set(el, handle);
+    let step = 0;
+    handle.s = setInterval(() => {
+      let s = '';
+      for (let i = 0; i < len; i++) s += glyph();
+      el.textContent = s;
+      if (++step < scrambleSteps) return;
+      clearInterval(handle.s); handle.s = null;
+      let resolved = 0;
+      handle.r = setInterval(() => {
+        resolved++;
+        let s = finalText.slice(0, resolved);
+        for (let i = resolved; i < len; i++) s += glyph();
+        el.textContent = s;
+        if (resolved < len) return;
+        clearInterval(handle.r); handle.r = null;
+        el.textContent = finalText;
+        el.classList.remove('glitching');
+        _scrambleHandles.delete(el);
+      }, resolveStepMs);
+    }, stepMs);
+  }
+
+  root.HUD = { pad, startClock, startSignal, scrambleReveal };
+
+  // Auto-bind: every overlay has #clock and #signal in the shared partial.
+  document.addEventListener('DOMContentLoaded', () => {
+    startClock(document.getElementById('clock'));
+    const sigEl = document.getElementById('signal');
+    if (sigEl) {
+      const profile = sigEl.dataset.profile || 'normal';
+      startSignal(sigEl, { profile });
+    }
+  });
+})(typeof window !== 'undefined' ? window : globalThis);