frame-panel
A spatial UI panel pinned to an XR reference frame (see xr-frames).
You give it a frame, a position (or a preset), and a placeholder title or your own
SVG; it renders the panel there and reveals it as you look toward it (gazeReveal).
This is the substrate for body-anchored UI — a waist "quick access / holster"
panel revealed by looking down, inventory panels over either shoulder revealed by
glancing back. The panel is FIXED in its frame (it doesn't billboard); the frame
itself moves (e.g. body follows your torso), so the panel rides with you and is
oriented once to face your head.
Anchor presets (in the body frame, metres; y is absolute since body sits at
the floor): waist, left-shoulder, right-shoulder.