feat: bump immersive visualizer to 60fps

Was hardcoded at 15fps (not the 30fps from config). Updated both
the canvas frame throttle and the default config to 60fps.

src/lib/immersive/ImmersiveAmbientCanvas.svelte

@@ -80,9 +80,8 @@
   let lastFrameTime = 0;
   let isVisible = true;
 
-  // Frame throttling for power efficiency
+  // Frame throttling
-  // 15fps is enough for slow ambient motion, saves significant CPU
+  const TARGET_FPS = 60;
-  const TARGET_FPS = 15;
   const FRAME_INTERVAL = 1000 / TARGET_FPS;
 
   /**

src/lib/immersive/types.ts

@@ -56,7 +56,7 @@ export interface ImmersiveConfig {
 
 /** Default configuration */
 export const DEFAULT_IMMERSIVE_CONFIG: ImmersiveConfig = {
-  targetFps: 30,
+  targetFps: 60,
   ambientIntensity: 1.0, // Full intensity for maximum ambient motion
   pauseWhenHidden: true,
   debugOverlay: false,