fix(handtracking): reduce GPU pressure on WebGL context loss

Several mitigations against the WebGL context lost that fires when
hand tracking starts on a loaded scene:

- Canvas: fixed DPR [1,1], antialias off, scoped id="game-canvas",
  context-lost handler releases MediaPipe and logs GPU memory counters
- optimizeGLTFScene: cap anisotropy at 2 and stop forcing mipmaps /
  needsUpdate on every pass — avoids massive texture re-uploads
- MediaPipe: force CPU delegate (HAND_TRACKING_BROWSER_DELEGATE),
  cache the landmarker instance, and expose releaseBrowserHandLandmarker
- useBrowserHandTracking / useRemoteHandTracking: idempotent cleanup
  guarded by a cleanedUp flag, try/catch around the detect loop, and
  release of the landmarker on stop
- World: mount HandTrackingGlove only when the matching hand is
  actually present in the snapshot (status connected + hands.length > 0)
- HandTrackingGlove: drop the eager useGLTF.preload that was running
  at startup whether or not hand tracking was used

Does not yet absorb the React StrictMode double-mount — that is the
follow-up commit.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/components/three/handTracking/HandTrackingGlove.tsx

@@ -1,7 +1,6 @@
 import type { ReactNode } from "react";
 import { Component, useEffect, useMemo, useRef } from "react";
 import { useFrame, useThree } from "@react-three/fiber";
-import { useGLTF } from "@react-three/drei";
 import * as THREE from "three";
 import { SkeletonUtils } from "three-stdlib";
 import { useHandTrackingSnapshot } from "@/hooks/handTracking/useHandTrackingSnapshot";
@@ -362,6 +361,3 @@ export function HandTrackingGlove({
     </HandTrackingGloveErrorBoundary>
   );
 }
-
-useGLTF.preload(GLOVE_CONFIGS.left.modelPath);
-useGLTF.preload(GLOVE_CONFIGS.right.modelPath);