ui/phase-19: ship-group decoder + map binding + selection store

Wires Phase 19's data and rendering layers without yet adding the
inspector UI:

  - game-state.ts grows ReportLocalShipGroup / ReportOtherShipGroup
    / ReportIncomingShipGroup / ReportUnidentifiedShipGroup /
    ReportLocalFleet types and walks the matching FlatBuffers
    vectors (LocalGroup, OtherGroup, IncomingGroup,
    UnidentifiedGroup, LocalFleet) inside decodeReport. The Tech
    map is folded into the fixed-shape ShipGroupTech struct;
    cargo strings normalise to the closed CargoLoadType | "NONE"
    union; UUIDs come back as canonical 36-char strings.
  - synthetic-report.ts mirrors the new fields so the DEV-only
    lobby loader can feed JSON produced by legacy-report-to-json
    straight into the live UI surface.
  - selection.svelte.ts widens its discriminated union with a
    `kind: "shipGroup"` branch carrying a ShipGroupRef
    (local UUID / other / incoming / unidentified by index).
  - world.ts adds Style.strokeDashPx and render.ts.drawLine
    honours it via manual segmentation (PixiJS v8 has no native
    dash API). Ignored on points and circles.
  - state-binding.ts now returns { world, hitLookup }: the
    hit-lookup map keys every primitive id back to a concrete
    HitTarget so the click handler can dispatch to selectPlanet
    or selectShipGroup. Ship-group primitives live in a separate
    ship-groups.ts that emits one point per local / other /
    unidentified group, plus a dashed origin→destination line +
    clickable point per incoming group. Position is interpolated
    along the trajectory for in-hyperspace groups.
  - map.svelte threads the hitLookup into handleMapClick.

Vitest:
  - tests/helpers/empty-ship-groups.ts exposes EMPTY_SHIP_GROUPS
    so existing fixtures can spread the new five empty arrays
    without enumerating every field.
  - state-binding-groups.test.ts covers each group variant's
    primitive geometry and lookup correctness.
  - All previously-existing fixture builders pick up the spread
    so GameReport stays a complete object.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

ui/frontend/tests/state-binding.test.ts

@@ -11,6 +11,7 @@ import { describe, expect, test } from "vitest";
 
 import type { GameReport, ReportPlanet } from "../src/api/game-state";
 import { reportToWorld } from "../src/map/state-binding";
+import { EMPTY_SHIP_GROUPS } from "./helpers/empty-ship-groups";
 
 function makeReport(overrides: Partial<GameReport> = {}): GameReport {
 	return {
@@ -26,6 +27,7 @@ function makeReport(overrides: Partial<GameReport> = {}): GameReport {
 		localPlayerWeapons: 0,
 		localPlayerShields: 0,
 		localPlayerCargo: 0,
+		...EMPTY_SHIP_GROUPS,
 		...overrides,
 	};
 }
@@ -55,13 +57,13 @@ function makePlanet(overrides: Partial<ReportPlanet>): ReportPlanet {
 
 describe("reportToWorld", () => {
 	test("uses report dimensions for the World", () => {
-		const world = reportToWorld(makeReport({ mapWidth: 3200, mapHeight: 1600 }));
+		const { world } = reportToWorld(makeReport({ mapWidth: 3200, mapHeight: 1600 }));
 		expect(world.width).toBe(3200);
 		expect(world.height).toBe(1600);
 	});
 
 	test("emits one Point primitive per planet across all four kinds", () => {
-		const world = reportToWorld(
+		const { world } = reportToWorld(
 			makeReport({
 				planets: [
 					makePlanet({ number: 1, name: "Home", x: 100, y: 100, kind: "local", size: 12, resources: 0.5 }),
@@ -78,7 +80,7 @@ describe("reportToWorld", () => {
 	});
 
 	test("propagates planet number as primitive id and coordinates verbatim", () => {
-		const world = reportToWorld(
+		const { world } = reportToWorld(
 			makeReport({
 				planets: [
 					makePlanet({ number: 42, name: "Home", x: 123.5, y: 456.25, kind: "local", size: 10, resources: 0.5 }),
@@ -95,7 +97,7 @@ describe("reportToWorld", () => {
 	});
 
 	test("uses distinct styles for each planet kind", () => {
-		const world = reportToWorld(
+		const { world } = reportToWorld(
 			makeReport({
 				planets: [
 					makePlanet({ number: 1, name: "L", kind: "local", size: 1, resources: 0 }),
@@ -111,14 +113,14 @@ describe("reportToWorld", () => {
 	});
 
 	test("zero-planet report yields an empty primitive list and well-formed World", () => {
-		const world = reportToWorld(makeReport({ planets: [] }));
+		const { world } = reportToWorld(makeReport({ planets: [] }));
 		expect(world.primitives.length).toBe(0);
 		expect(world.width).toBeGreaterThan(0);
 		expect(world.height).toBeGreaterThan(0);
 	});
 
 	test("guards against zero / negative dimensions in the report", () => {
-		const world = reportToWorld(
+		const { world } = reportToWorld(
 			makeReport({ mapWidth: 0, mapHeight: -1, planets: [] }),
 		);
 		// World's constructor rejects non-positive dimensions; the
@@ -129,7 +131,7 @@ describe("reportToWorld", () => {
 	});
 
 	test("local planets carry higher priority than unidentified", () => {
-		const world = reportToWorld(
+		const { world } = reportToWorld(
 			makeReport({
 				planets: [
 					makePlanet({ number: 1, name: "Home", kind: "local", size: 1, resources: 0 }),
@@ -148,7 +150,7 @@ describe("reportToWorld", () => {
 		// into `reportToWorld`. The base world stays a clean
 		// representation of the report's planets so the renderer
 		// can rebuild the overlay without disposing Pixi.
-		const world = reportToWorld(
+		const { world } = reportToWorld(
 			makeReport({
 				planets: [
 					makePlanet({ number: 1, name: "Earth", x: 100, y: 100, kind: "local", size: 5, resources: 1 }),