Plot routes and build the jump-link graph in a Web Worker

Route plotting ran on the main thread, and so did the jump-link graph:

- the range search for a far target, HD 2626 at 236 pc, takes 4-5 s;
- the graph at 8 pc is 3.7 million links, 6-10 s to build, then as many
  link objects again to turn into vertices.

The map stopped for as long as either ran.

A Web Worker now does both. RoutingClient sends it the catalogue's ids and
positions once, and it keeps its own spatial index. A route question comes
back with the route, or with the range that would open one. A graph comes
back as one Float32Array of segment vertices, transferred rather than
copied.

On the scene side, only the latest route request is shown: an earlier
answer arriving later is dropped. Only the graph for the range last asked
for is drawn. The Routes panel says "Plotting…" and holds its button while
a request is out.

collectJumpLinks gave way to jumpLinkSegments, which writes the vertex pairs
straight into floats rather than building link objects first; the scene was
its only caller. The routing module (routing.ts) is the message protocol and
the one function answering it, so the worker is a dozen lines, and the same
answers are worked out in place where there is no Worker, as in the unit
tests' DOM. The worker is built with its own tsconfig, as the Angular
builder expects.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016jxMkwA2rbicdGxHosecYi

src/app/features/galaxy-system/jump-link-renderer.ts

@@ -1,7 +1,5 @@
 import * as THREE from 'three/webgpu';
 
-import { JumpLink } from '../../shared/astro/jump-links';
-
 /** Faint, because there are tens of thousands of them and none is worth reading on its own. */
 const LINK_OPACITY = 0.16;
 /** The one route is the figure; the graph it is drawn on is the ground. */
@@ -48,23 +46,13 @@ export class JumpLinkRenderer {
     this.links.frustumCulled = false;
     this.route.frustumCulled = false;
     this.object.add(this.links, this.route);
-    this.setLinks([], () => undefined);
+    this.setSegments(new Float32Array(0));
     this.setRoute([], () => undefined);
   }
 
-  setLinks(links: readonly JumpLink[], positionOf: (starId: number) => LinkPoint | undefined): void {
-    const vertices = new Float32Array(links.length * 6);
-    let at = 0;
-    for (const link of links) {
-      const from = positionOf(link.from);
-      const to = positionOf(link.to);
-      if (!from || !to) {
-        continue;
-      }
-      vertices.set([from.x, from.y, from.z, to.x, to.y, to.z], at);
-      at += 6;
-    }
-    this.replaceGeometry(this.links, at === vertices.length ? vertices : vertices.subarray(0, at));
+  /** The graph, as vertex pairs: six floats a link, one end then the other. See `jumpLinkSegments`. */
+  setSegments(vertices: Float32Array): void {
+    this.replaceGeometry(this.links, vertices);
   }
 
   /** The chain to draw over the graph, departure first. Fewer than two stars draws nothing. */