Add a drag-and-resize animation

A drawn pointer grabs the frame near its top edge, drags it across the
screen, lets go, then takes hold of one corner and pulls the frame to a
new size. Moves ease in and overshoot slightly before settling, and the
paths bow, so the motion reads as a hand rather than a tween.

The resize pins the opposite corner and keeps the aspect ratio locked —
a stretched video would read as broken, not as someone resizing — and
clamps the width to the room left before the corner leaves the screen.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Tg15tLAuT6NrCE1ZxKVgDB

server/index.js

@@ -15,6 +15,8 @@ import {
   BOUNCE_SPEED,
   CORNER_INTERVAL_SECONDS,
   CORNER_MARGIN,
+  DRAG_MIN_SCALE,
+  DRAG_MAX_SCALE,
   BACKGROUNDS,
   ANIMATIONS,
   AUTO_ANIMATION,
@@ -45,6 +47,8 @@ app.get('/config.js', (_req, res) => {
       `export const BOUNCE_SPEED = ${BOUNCE_SPEED};\n` +
       `export const CORNER_INTERVAL_SECONDS = ${CORNER_INTERVAL_SECONDS};\n` +
       `export const CORNER_MARGIN = ${CORNER_MARGIN};\n` +
+      `export const DRAG_MIN_SCALE = ${DRAG_MIN_SCALE};\n` +
+      `export const DRAG_MAX_SCALE = ${DRAG_MAX_SCALE};\n` +
       `export const BACKGROUNDS = ${JSON.stringify(BACKGROUNDS)};\n` +
       `export const ANIMATIONS = ${JSON.stringify(ANIMATIONS)};\n` +
       `export const AUTO_ANIMATION = ${JSON.stringify(AUTO_ANIMATION)};\n`,