feat: Emberwake, Crucible phases, Linux agent, musical dashboard, e2e

Emberwake spread/waterhole UI, campaign DB, spread handler, spread-kit web publisher, and SPREAD_TECHNIQUES doc. Crucible Phase A-C: expanded ops, port-forward matrix, remote dir browser, crucible help/tests.

Linux agent hardening: credential vault, persistence audit, firewall/defender deploy, SMB spread status, CPU stats, screenshots/crypt/file-ops split. Docker compose and agent/server images with e2e validation script and docs.

Musical dashboard: ambient music player, hover SFX, SoundContext/AmbientMusicContext, steampunk polish. Public builds API, dropper handler updates, SessionGate and fleet UX. README and PROBLEMS.md refresh.

server/web/src/components/GlobalMusicPlayer.tsx

@@ -0,0 +1,48 @@
+import { useAmbientMusic } from '../context/AmbientMusicContext';
+import './GlobalMusicPlayer.css';
+
+export default function GlobalMusicPlayer() {
+  const { enabled, playing, volume, setVolume, togglePlay } = useAmbientMusic();
+
+  return (
+    <div
+      className="global-music-player"
+      data-sfx="off"
+      role="region"
+      aria-label="Background music controls"
+    >
+      <button
+        type="button"
+        className="global-music-player__play"
+        onClick={togglePlay}
+        aria-label={playing ? 'Pause background music' : 'Play background music'}
+        title={playing ? 'Pause music' : enabled ? 'Play music' : 'Enable & play music'}
+      >
+        {playing ? (
+          <svg viewBox="0 0 24 24" aria-hidden="true">
+            <rect x="6" y="5" width="4" height="14" rx="1" fill="currentColor" />
+            <rect x="14" y="5" width="4" height="14" rx="1" fill="currentColor" />
+          </svg>
+        ) : (
+          <svg viewBox="0 0 24 24" aria-hidden="true">
+            <path d="M8 5v14l11-7z" fill="currentColor" />
+          </svg>
+        )}
+      </button>
+      <label className="global-music-player__vol" title="Music volume">
+        <span className="sr-only">Music volume</span>
+        <input
+          type="range"
+          min={0}
+          max={100}
+          step={5}
+          value={Math.round(volume * 100)}
+          onChange={(e) => setVolume(parseInt(e.target.value, 10) / 100)}
+          aria-valuenow={Math.round(volume * 100)}
+          aria-valuemin={0}
+          aria-valuemax={100}
+        />
+      </label>
+    </div>
+  );
+}