Answer the review: one reference viewport, one lookup for the card

Two of the three comments were worth taking.

The star field and the rings drawn over it each carried their own copy of the
reference viewport and field of view the angular sizes are figured against.
They agree today, and nothing would have told anyone when they stopped: a ring
would just sit a little wide of its star at some window sizes. One module now
holds the three constants and says what they are for.

The leader line to the object card looked the card's panel up by selector on
every frame it was drawn. The host element is stable and the panel inside it
only changes when a different body is selected, so the lookup is derived once
per change instead of sixty times a second.

Left alone: replacing `positions.set([x, y, z], i * 3)` with an index-by-index
loop to avoid a temporary array per host. It runs once, over six hundred and
thirty-four stars, at bootstrap, and the version with the temporary reads
better than the version without.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016jxMkwA2rbicdGxHosecYi

src/app/features/galaxy-system/host-star-rings.ts

@@ -2,14 +2,11 @@ import * as THREE from 'three/webgpu';
 import { color, float, instancedBufferAttribute, smoothstep, uniform, uv, vec2 } from 'three/tsl';
 
 import { StarRecord } from '../../shared/models/star.model';
+import { PIXELS_TO_ANGULAR_SIZE } from './angular-size';
 
 /** Ring diameter in screen pixels at the reference viewport — angular, like the star points. */
 const RING_SIZE_PX = 12;
 const RING_PEAK_OPACITY = 0.35;
-/** Same reference as `StarFieldRenderer`, so a ring and its star agree on what a pixel is. */
-const REFERENCE_VIEWPORT_HEIGHT_PX = 900;
-const REFERENCE_FOV_DEGREES = 55;
-const PIXELS_TO_ANGULAR_SIZE = (2 * Math.tan((REFERENCE_FOV_DEGREES * Math.PI) / 180 / 2)) / REFERENCE_VIEWPORT_HEIGHT_PX;
 /** Ring radius and stroke half-width in quad-uv units (the quad runs 0..1, centre 0.5). */
 const RING_RADIUS_UV = 0.42;
 const RING_STROKE_UV = 0.06;