feat(combat): add 'overwhelm' win condition with visual effects and result display

- Introduces `winType` field to track victory conditions (commander/depletion/overwhelm)
- Implements `_overwhelmCheck()` logic to detect when one side exhausts all resources while the other retains combat capability
- Adds `_animateOverwhelm()` sequence: banner, rally, strikes, HP drain, and commander defeat with shake/flash/particle effects
- Updates `BattleResultScene` to show "VICTORY BY OVERWHELM!" / "OVERWHELMED" titles and annotate report accordingly

src/scenes/BattleScene.js

@@ -219,21 +219,21 @@ export class BattleScene extends Phaser.Scene {
     this.playerGoesFirst = true;
     this.initiativeIndicator = null;
 
-    const autoBtn = this.add.rectangle(1680, 35, 180, 44, 0x224422)
+    this.autoBtn = this.add.rectangle(1680, 35, 180, 44, 0x224422)
       .setInteractive({ useHandCursor: true })
       .setStrokeStyle(1, 0x44aa44);
     this.autoBtnText = this.add.text(1680, 35, 'Auto: OFF', {
       fontSize: '18px', color: '#ffffff', fontFamily: 'Audiowide'
     }).setOrigin(0.5);
-    autoBtn.on('pointerdown', () => this._toggleAuto());
+    this.autoBtn.on('pointerdown', () => this._toggleAuto());
 
-    const nextBtn = this.add.rectangle(1840, 35, 180, 44, 0x1a3a5c)
+    this.nextBtn = this.add.rectangle(1840, 35, 180, 44, 0x1a3a5c)
       .setInteractive({ useHandCursor: true })
       .setStrokeStyle(1, 0x4488ff);
-    this.add.text(1840, 35, 'Next Turn', {
+    this.nextBtnText = this.add.text(1840, 35, 'Next Turn', {
       fontSize: '18px', color: '#ffffff', fontFamily: 'Audiowide'
     }).setOrigin(0.5);
-    nextBtn.on('pointerdown', () => this._beginTurn());
+    this.nextBtn.on('pointerdown', () => this._beginTurn());
 
     // Keyboard
     this.input.keyboard.on('keydown-SPACE', () => this._beginTurn());
@@ -761,6 +761,7 @@ export class BattleScene extends Phaser.Scene {
   }
 
   _beginTurn() {
+    this._clearNextTurnHint();
     if (this._tutorialActive) return;
     if (this.waitingForPick || this.isAnimating) return;
     if (this.engine.winner) { this._showResult(); return; }
@@ -924,6 +925,7 @@ export class BattleScene extends Phaser.Scene {
           this._animateInitiativeHandoff();
           this.isAnimating = false;
           this.statusText.setText('Press SPACE or click Next Turn to advance');
+          if (!this.autoPlay) this._startNextTurnHint();
         }
       });
       return;
@@ -4738,10 +4740,76 @@ export class BattleScene extends Phaser.Scene {
     });
   }
 
+  _startNextTurnHint() {
+    this._clearNextTurnHint();
+    const btnX = 1840, btnY = 35;
+
+    // After 2s: yellow arrow that bobs up and down below the Next Turn button
+    this._nextTurnHintTimer1 = this.time.delayedCall(2000, () => {
+      if (this.autoPlay || this.isAnimating || this.waitingForPick) return;
+      this._nextTurnArrow = this.add.text(btnX, btnY + 50, '▲', {
+        fontSize: '32px', color: '#ffdd00', fontFamily: 'Audiowide'
+      }).setOrigin(0.5).setDepth(101);
+
+      this.tweens.add({
+        targets: this._nextTurnArrow,
+        y: { from: btnY + 44, to: btnY + 58 },
+        duration: 450,
+        yoyo: true,
+        repeat: -1,
+        ease: 'Sine.easeInOut'
+      });
+    });
+
+    // After 5s: dim the screen, lift the buttons above the overlay, show hint text
+    this._nextTurnHintTimer2 = this.time.delayedCall(5000, () => {
+      if (this.autoPlay || this.isAnimating || this.waitingForPick) return;
+
+      // Full-screen dim overlay
+      const { width, height } = this.scale;
+      this._nextTurnDim = this.add.rectangle(width / 2, height / 2, width, height, 0x000000, 0.55)
+        .setDepth(98);
+
+      // Lift buttons above the dim
+      this.autoBtn.setDepth(99);
+      this.autoBtnText.setDepth(99);
+      this.nextBtn.setDepth(99);
+      this.nextBtnText.setDepth(99);
+
+      // Bring arrow above the dim too
+      if (this._nextTurnArrow) this._nextTurnArrow.setDepth(101);
+
+      // Hint text — right-aligned so it stays within the screen
+      this._nextTurnHintLabel = this.add.text(1910, btnY + 95, "Click 'Next' to begin the next turn", {
+        fontSize: '16px', color: '#ffffff', fontFamily: 'Audiowide'
+      }).setOrigin(1, 0.5).setDepth(101);
+
+      this.tweens.add({
+        targets: this._nextTurnHintLabel,
+        alpha: { from: 1, to: 0.3 },
+        duration: 800,
+        yoyo: true,
+        repeat: -1
+      });
+    });
+  }
+
+  _clearNextTurnHint() {
+    if (this._nextTurnHintTimer1) { this._nextTurnHintTimer1.remove(); this._nextTurnHintTimer1 = null; }
+    if (this._nextTurnHintTimer2) { this._nextTurnHintTimer2.remove(); this._nextTurnHintTimer2 = null; }
+    if (this._nextTurnArrow) { this.tweens.killTweensOf(this._nextTurnArrow); this._nextTurnArrow.destroy(); this._nextTurnArrow = null; }
+    if (this._nextTurnHintLabel) { this.tweens.killTweensOf(this._nextTurnHintLabel); this._nextTurnHintLabel.destroy(); this._nextTurnHintLabel = null; }
+    if (this._nextTurnDim) { this._nextTurnDim.destroy(); this._nextTurnDim = null; }
+    // Reset button depths
+    if (this.autoBtn) { this.autoBtn.setDepth(0); this.autoBtnText.setDepth(0); }
+    if (this.nextBtn) { this.nextBtn.setDepth(0); this.nextBtnText.setDepth(0); }
+  }
+
   _toggleAuto() {
     this.autoPlay = !this.autoPlay;
     this.autoBtnText.setText(`Auto: ${this.autoPlay ? 'ON' : 'OFF'}`);
     if (this.autoPlay) {
+      this._clearNextTurnHint();
       this.autoTimer = this.time.addEvent({
         delay: 300,
         callback: () => {