feat: add toggleable red glow highlight on followed NPC

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

client/src/scenes/GameScene.ts

@@ -31,6 +31,8 @@ export class GameScene extends Phaser.Scene {
   private emojiManager!: InteractionEmojiManager;
   private commandPanel!: CommandPanel;
   private followCommandPanel!: CommandPanel;
+  private highlightEnabled = false;
+  private highlightedSpriteId: number | null = null;
 
   constructor() {
     super({ key: 'GameScene' });
@@ -89,6 +91,8 @@ export class GameScene extends Phaser.Scene {
       } else if (prevMode === 'follow') {
         this.npcInfoPanel.hide();
         this.followCommandPanel.hide();
+        this.clearHighlight();
+        this.highlightEnabled = false;
       }
 
       // Command panel visibility
@@ -101,6 +105,17 @@ export class GameScene extends Phaser.Scene {
 
     // Spawn NPC command (camera mode only)
     this.input.keyboard!.addKey('ONE').on('down', () => {
+      if (this.mode === 'follow') {
+        this.highlightEnabled = !this.highlightEnabled;
+        if (this.highlightEnabled) {
+          const npcIds = this.getNpcIds();
+          const targetId = npcIds[this.followTargetIndex];
+          if (targetId != null) this.applyHighlight(targetId);
+        } else {
+          this.clearHighlight();
+        }
+        return;
+      }
       if (this.mode !== 'camera') return;
       const cam = this.cameras.main;
       const centerTileX = Math.floor((cam.scrollX + cam.width / 2) / TILE_SIZE);
@@ -265,6 +280,9 @@ export class GameScene extends Phaser.Scene {
     for (const [id, es] of this.entitySprites) {
       if (!activeIds.has(id)) {
         es.sprite.destroy();
+        if (id === this.highlightedSpriteId) {
+          this.highlightedSpriteId = null;
+        }
         this.entitySprites.delete(id);
       }
     }
@@ -354,11 +372,17 @@ export class GameScene extends Phaser.Scene {
         if (left) {
           this.followTargetIndex = (this.followTargetIndex - 1 + npcIds.length) % npcIds.length;
           this.followThrottle = 150;
+          if (this.highlightEnabled) {
+            this.applyHighlight(npcIds[this.followTargetIndex]);
+          }
           this.updateModeText();
           this.updateFollowPanel();
         } else if (right) {
           this.followTargetIndex = (this.followTargetIndex + 1) % npcIds.length;
           this.followThrottle = 150;
+          if (this.highlightEnabled) {
+            this.applyHighlight(npcIds[this.followTargetIndex]);
+          }
           this.updateModeText();
           this.updateFollowPanel();
         }
@@ -414,4 +438,22 @@ export class GameScene extends Phaser.Scene {
       this.modeText.setText(`Mode: ${this.mode.toUpperCase()} [TAB to toggle]`);
     }
   }
+
+  private applyHighlight(entityId: number): void {
+    const es = this.entitySprites.get(entityId);
+    if (!es) return;
+    this.clearHighlight();
+    es.sprite.postFX.addGlow(0xff0000, 2, 0, false, 0.1, 4);
+    this.highlightedSpriteId = entityId;
+  }
+
+  private clearHighlight(): void {
+    if (this.highlightedSpriteId != null) {
+      const es = this.entitySprites.get(this.highlightedSpriteId);
+      if (es) {
+        es.sprite.postFX.clear();
+      }
+      this.highlightedSpriteId = null;
+    }
+  }
 }