fix(calendar-lab): rewrite zoom as GSAP flying-rect with proper async sequencing

- Replace panzoom + timeline approach with clean async/await GSAP tweens
- Flying rect morphs from cell position to full viewport (aspect ratio change)
- Fix zoomOut race condition: nested gsap.to inside tl.call fired outside timeline
- Fix opacity conflict: GSAP controls all opacity, CSS class only for pointer-events
- Fix gridLayerRef losing reference on :key remount during resize
- Make viewport dimensions reactive via ResizeObserver (vpWidth/vpHeight refs)
- Wait for fade-in completion before unlocking isAnimating

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

frontend/package.json

@@ -42,6 +42,7 @@
     "daisyui": "^5.5.18",
     "graphql": "^16.12.0",
     "graphql-tag": "^2.12.6",
+    "gsap": "^3.14.2",
     "ioredis": "^5.7.0",
     "langfuse": "^3.38.6",
     "langsmith": "^0.5.4",