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Add star-map Angular app, ETL pipeline, and caveman plugin

Angular 3D star map (galaxy/system/body views, Three.js rendering,
navigation store) plus the NASA ETL tooling that builds the star,
exoplanet and solar-system datasets, Playwright e2e suite, and the
cs:caveman Claude Code plugin (command, agent, skill).

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
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src/app/shared/astro/coordinates.ts

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+const DEG_TO_RAD = Math.PI / 180;
+const HOURS_TO_DEG = 15;
+
+export interface CartesianCoordinates {
+  x: number;
+  y: number;
+  z: number;
+}
+
+/**
+ * Converts right ascension (hours), declination (degrees) and distance (parsecs) into
+ * equatorial Cartesian coordinates (parsecs). Matches the HYG database convention:
+ * +X toward the vernal equinox (epoch 2000), +Z toward the north celestial pole,
+ * +Y toward RA 6h / Dec 0.
+ */
+export function raDecDistanceToXyz(raHours: number, decDeg: number, distancePc: number): CartesianCoordinates {
+  const raRad = raHours * HOURS_TO_DEG * DEG_TO_RAD;
+  const decRad = decDeg * DEG_TO_RAD;
+  const cosDec = Math.cos(decRad);
+
+  return {
+    x: distancePc * cosDec * Math.cos(raRad),
+    y: distancePc * cosDec * Math.sin(raRad),
+    z: distancePc * Math.sin(decRad)
+  };
+}
+
+/**
+ * Same conversion as {@link raDecDistanceToXyz}, but for sources (e.g. exoplanet host
+ * stars, deep-sky catalogs) that report right ascension in degrees rather than hours.
+ */
+export function raDegDecDistanceToXyz(raDeg: number, decDeg: number, distancePc: number): CartesianCoordinates {
+  return raDecDistanceToXyz(raDeg / HOURS_TO_DEG, decDeg, distancePc);
+}
+
+/**
+ * Converts a parallax (milliarcseconds) into a distance in parsecs.
+ * Returns `Infinity` for non-positive parallax (unmeasured/negative parallax).
+ */
+export function parallaxMasToParsecs(parallaxMas: number): number {
+  return parallaxMas > 0 ? 1000 / parallaxMas : Infinity;
+}
+
+/**
+ * Euclidean distance (parsecs) between two Cartesian points, e.g. for nearest-neighbour
+ * star matching during exoplanet host-star cross-referencing.
+ */
+export function distanceBetween(a: CartesianCoordinates, b: CartesianCoordinates): number {
+  const dx = a.x - b.x;
+  const dy = a.y - b.y;
+  const dz = a.z - b.z;
+  return Math.sqrt(dx * dx + dy * dy + dz * dz);
+}