feat(studio): iPad screenshot support + cleanup

Generalize the studio into a Platform/DeviceModel abstraction so it renders
both iPhone and iPad sets from one code path.

- Platform: per-target canvas (iPad 2064x2752), 3D model, capture sim, and
  output subfolder (iPad -> <Language>/iPad/). PLATFORM=iphone|ipad.
- DeviceModel: screen material, orientation (yaw) fix, optional glass mesh,
  graphite recolor — the per-model quirks the renderer needs.
- SceneKit renderer: auto-generates planar UVs for screen meshes that ship
  without them; textures every material matching the screen name; zFar scaled
  for large-unit models; body recolor skips the real screen material.
- iPad uses a CC BY 4.0 model (commercial-safe) with real bezel geometry;
  first-pass iPad layouts for all four screens. capture.sh is PLATFORM-aware.

Remove now-dead code: the 2D mockup fallback (ClipDeviceRenderer,
MockupGeometry), the orbit ring and binary-tunnel (superseded by the route arc
and the encryption-flow), unused DeviceModel UV/inset workarounds; refresh the
README and .gitignore to match.

packaging/apple/studio/capture.sh

@@ -15,10 +15,16 @@ trap 'echo "capture.sh: failed (rc=$?) at line $LINENO" >&2' ERR
 cd "$(dirname "$0")"
 
 APPLE_DIR="$(cd ../../../apple && pwd)"
-DEVICE="${SCREENSHOT_DEVICE:-iPhone 17 Pro Max}"
 BUNDLE_ID="com.vnidrop.app"
 LOCALES=${LOCALES:-"en fr de es it nl pl pt ru"}
 
+# PLATFORM=iphone|ipad selects the simulator and the shots subdir (must match main.swift).
+PLATFORM="${PLATFORM:-iphone}"
+case "$PLATFORM" in
+	ipad) DEVICE="${SCREENSHOT_DEVICE:-iPad Pro 13-inch (M5)}";;
+	*)    DEVICE="${SCREENSHOT_DEVICE:-iPhone 17 Pro Max}";;
+esac
+
 # scenario (launch arg value) -> studio screen id (output filename stem).
 # send-anywhere reuses the share screenshot (see ScreenSpec shotId), so it isn't
 # captured separately; stay-private uses black screens (no capture).
@@ -26,7 +32,7 @@ SCENARIOS="share:share-securely approval:choose-receivers"
 
 # Screenshots are transient build output, regenerated per run — never committed. They
 # live under generated/ (git-ignored), not in assets/.
-SHOTS_DIR="${SHOTS_DIR:-generated/shots}"
+SHOTS_DIR="${SHOTS_DIR:-generated/shots/$PLATFORM}"
 
 echo "==> Regenerating project"; (cd "$APPLE_DIR" && xcodegen generate >/dev/null)