feat: enhance Shift backgrounds and add commander death SFX for TA

- Add background image support for Shift game menu screens
- Remove redundant title/subtitle text in Shift difficulty select
- Add nuclear explosion SFX for Total Annihilation commander deaths
- Extend _throttledSfx to support optional volume parameter

src/data/assetManifest.js

@@ -156,7 +156,10 @@ export const MANIFEST = {
     image('spireclimb-act3', 'assets/images/spireclimb-act3.png'),
     (scene) => sheetsFrom(scene, 'spireclimb-artwork', ['cardSheet', 'creatureSheet', 'playerSheets']),
   ],
-  shift: (scene) => imagesFrom(scene, 'shift-artwork'),
+  shift: [
+    image('shift-background', 'assets/images/background-shift.png'),
+    (scene) => imagesFrom(scene, 'shift-artwork'),
+  ],
   slots: (scene) => imagesFrom(scene, 'slots-artwork'),
   dungeonboss: (scene) => sheetsFrom(scene, 'dungeonboss-artwork',
     ['roomSheet', 'heroSheet', 'spellSheet', 'bossSheet', 'deckBackSheet', 'iconSheet']),
@@ -278,7 +281,7 @@ export const MANIFEST = {
     { type: 'audio', key: 'sfx-scifi-launch', path: 'assets/fx/scifi-launch.mp3' },
     // TA-specific sfx: machine guns per weapon.sound, rocket variants (random pick between the
     // two on fire, see TotalAnnihilationGame._onSimEvent), and unit/vehicle death cues.
-    ...['50cal', 'machinegun', 'rocket-1', 'rocket-2', 'unit-loss', 'vehicle-loss']
+    ...['50cal', 'machinegun', 'rocket-1', 'rocket-2', 'nuclear', 'unit-loss', 'vehicle-loss']
       .map((n) => ({ type: 'audio', key: `sfx-ta-${n}`, path: `assets/fx/ta-${n}.mp3` })),
     (scene) => musicFrom(scene, 'hacker-music'),
   ],

src/games/shift/ShiftGame.js

@@ -83,24 +83,26 @@ export default class ShiftGame extends Phaser.Scene {
     this.bestText  = null;
   }
 
+  _drawMenuBackground() {
+    if (this.textures.exists('shift-background')) {
+      this.add.image(GAME_WIDTH / 2, GAME_HEIGHT / 2, 'shift-background')
+        .setDisplaySize(GAME_WIDTH, GAME_HEIGHT).setDepth(D.bg);
+    }
+  }
+
   // ── Difficulty select ─────────────────────────────────────────────────────────
 
   showDifficultySelect() {
     this.view = 'difficulty';
     this.overlayUp = false;
     this.clearLayer();
+    this._drawMenuBackground();
     const cx = GAME_WIDTH / 2;
 
-    const title = this.add.text(cx, 160, 'SHIFT', {
-      fontFamily: 'Righteous', fontSize: '96px', color: COLORS.goldHex,
-    }).setOrigin(0.5);
-    const sub = this.add.text(cx, 268, 'Slide tiles into the empty space to restore the image.', {
-      fontFamily: '"Julius Sans One"', fontSize: '30px', color: COLORS.mutedHex,
-    }).setOrigin(0.5);
-    const pick = this.add.text(cx, 356, 'Choose a difficulty', {
+    const pick = this.add.text(cx, 390, 'Choose a difficulty', {
       fontFamily: 'Righteous', fontSize: '34px', color: COLORS.textHex,
     }).setOrigin(0.5);
-    this.layer.add([title, sub, pick]);
+    this.layer.add(pick);
 
     const TILE_W   = 430;
     const TILE_H   = 400;
@@ -218,6 +220,7 @@ export default class ShiftGame extends Phaser.Scene {
     this.view = 'artwork';
     this.overlayUp = false;
     this.clearLayer();
+    this._drawMenuBackground();
     const cx = GAME_WIDTH / 2;
 
     const title = this.add.text(cx, 120, 'Choose Your Image', {

src/games/totalannihilation/TotalAnnihilationGame.js

@@ -13,7 +13,7 @@ import * as Phaser from 'phaser';
 import { GAME_WIDTH, GAME_HEIGHT } from '../../config.js';
 import { MusicPlayer } from '../../ui/MusicPlayer.js';
 import { getGameSoundtrack } from '../../services/soundtrack.js';
-import { playSound } from '../../ui/Sounds.js';
+import { playSound, playSoundEx } from '../../ui/Sounds.js';
 import { api } from '../../services/api.js';
 import { compileRules } from './TARules.js';
 import { generateMap, decodeMap } from './TAMapGen.js';
@@ -263,8 +263,13 @@ export default class TotalAnnihilationGame extends Phaser.Scene {
     if (ev.t === 'weaponFired' && ev.sound) this._throttledSfx(this._pickSound(ev.sound), 90);
     if (ev.t === 'impact' && ev.sound) this._throttledSfx(this._pickSound(ev.sound), 90);
     if (ev.t === 'unitDestroyed' && !ev.isBuilding) {
-      const moveClass = this.rules.defById[ev.defId]?.moveClass;
-      if (moveClass) this._throttledSfx(moveClass === 'foot' ? 'sfx-ta-unit-loss' : 'sfx-ta-vehicle-loss', 120);
+      const def = this.rules.defById[ev.defId];
+      if (def?.isCommander) {
+        // Play the nuclear explosion at full volume for maximum impact
+        this._throttledSfx('sfx-ta-nuclear', 300, 1);
+      } else if (def?.moveClass) {
+        this._throttledSfx(def.moveClass === 'foot' ? 'sfx-ta-unit-loss' : 'sfx-ta-vehicle-loss', 120);
+      }
     }
     if (ev.t === 'buildingComplete' && ev.army === this.playerArmy) {
       // Terrain under a finished structure changes, so its chunk has to be restamped.
@@ -290,12 +295,19 @@ export default class TotalAnnihilationGame extends Phaser.Scene {
   }
 
   /** Gate repeated plays of the same sound key so a volley of units firing at once doesn't
-   *  stack a dozen overlapping instances of the same clip. */
-  _throttledSfx(key, gapMs) {
+   *  stack a dozen overlapping instances of the same clip.
+   *  @param {string} key - Sound key
+   *  @param {number} gapMs - Minimum ms between plays
+   *  @param {number} [volume] - Optional volume 0-1 (defaults to normal via playSound) */
+  _throttledSfx(key, gapMs, volume) {
     const now = this.time.now;
     if ((this.lastSfxAt[key] ?? -1e9) + gapMs > now) return;
     this.lastSfxAt[key] = now;
-    playSound(this, key);
+    if (volume !== undefined) {
+      playSoundEx(this, key, { volume });
+    } else {
+      playSound(this, key);
+    }
   }
 
   _finish(over) {