feat: Implement Story 1.6 - Move Shared Defs Resources to the Dedicated Host

- Added documentation for Story 1.6 outlining the requirements and acceptance criteria for migrating shared defs-backed resources to a dedicated host.
- Updated sprint status to reflect the readiness of Story 1.6 for development.
- Created epics document detailing the breakdown of the Fantasy-Map-Generator project, including functional and non-functional requirements.
- Added implementation readiness report assessing the current state of documentation and readiness for the project.
- Introduced end-to-end tests for scene bootstrap to ensure runtime hosts are created and reused correctly.

tests/e2e/scene-bootstrap.spec.ts

@@ -0,0 +1,100 @@
+import path from "path";
+import { expect, test } from "@playwright/test";
+
+async function collectCriticalErrors(page: import("@playwright/test").Page, action: () => Promise<void>) {
+  const errors: string[] = [];
+
+  page.on("pageerror", error => errors.push(`pageerror: ${error.message}`));
+  page.on("console", message => {
+    if (message.type() === "error") {
+      errors.push(`console.error: ${message.text()}`);
+    }
+  });
+
+  await action();
+
+  return errors.filter(
+    error =>
+      !error.includes("fonts.googleapis.com") &&
+      !error.includes("google-analytics") &&
+      !error.includes("googletagmanager") &&
+      !error.includes("Failed to load resource"),
+  );
+}
+
+test.describe("scene bootstrap", () => {
+  test.beforeEach(async ({ context, page }) => {
+    await context.clearCookies();
+    await page.goto("/");
+    await page.evaluate(() => {
+      localStorage.clear();
+      sessionStorage.clear();
+    });
+  });
+
+  test("creates runtime hosts on fresh load", async ({ page }) => {
+    const criticalErrors = await collectCriticalErrors(page, async () => {
+      await page.goto("/?seed=test-scene-bootstrap&width=1280&height=720");
+      await page.waitForFunction(() => (window as any).mapId !== undefined, {timeout: 60000});
+    });
+
+    const runtimeHosts = await page.evaluate(() => {
+      const mapContainer = document.getElementById("map-container");
+      const sceneContainer = document.getElementById("map-scene");
+      const defsHost = document.getElementById("runtime-defs-host");
+      const map = document.getElementById("map");
+      const canvas = document.getElementById("webgl-canvas");
+
+      return {
+        hasMapContainer: !!mapContainer,
+        hasSceneContainer: !!sceneContainer,
+        hasDefsHost: !!defsHost,
+        mapInsideScene: !!sceneContainer?.contains(map),
+        canvasInsideScene: !!sceneContainer?.contains(canvas),
+        defsOutsideScene: !!defsHost && !!sceneContainer && !sceneContainer.contains(defsHost),
+      };
+    });
+
+    expect(runtimeHosts.hasMapContainer).toBe(true);
+    expect(runtimeHosts.hasSceneContainer).toBe(true);
+    expect(runtimeHosts.hasDefsHost).toBe(true);
+    expect(runtimeHosts.mapInsideScene).toBe(true);
+    expect(runtimeHosts.canvasInsideScene).toBe(true);
+    expect(runtimeHosts.defsOutsideScene).toBe(true);
+    expect(criticalErrors).toEqual([]);
+  });
+
+  test("reuses runtime hosts after loading a saved map", async ({ page }) => {
+    const criticalErrors = await collectCriticalErrors(page, async () => {
+      await page.goto("/");
+      await page.waitForSelector("#mapToLoad", {state: "attached"});
+      const mapFilePath = path.join(__dirname, "../fixtures/demo.map");
+      await page.locator("#mapToLoad").setInputFiles(mapFilePath);
+      await page.waitForFunction(() => (window as any).mapId !== undefined, {timeout: 120000});
+    });
+
+    const runtimeHosts = await page.evaluate(() => {
+      const sceneContainer = document.getElementById("map-scene");
+      const defsHost = document.getElementById("runtime-defs-host");
+      const map = document.getElementById("map");
+      const viewbox = document.getElementById("viewbox");
+      const deftemp = document.getElementById("deftemp");
+      const canvas = document.getElementById("webgl-canvas");
+
+      return {
+        hasSceneContainer: !!sceneContainer,
+        hasDefsHost: !!defsHost,
+        mapInsideScene: !!sceneContainer?.contains(map),
+        canvasInsideScene: !!sceneContainer?.contains(canvas),
+        rebuiltMapSelections: !!viewbox && !!deftemp,
+      };
+    });
+
+    expect(runtimeHosts.hasSceneContainer).toBe(true);
+    expect(runtimeHosts.hasDefsHost).toBe(true);
+    expect(runtimeHosts.mapInsideScene).toBe(true);
+    expect(runtimeHosts.canvasInsideScene).toBe(true);
+    expect(runtimeHosts.rebuiltMapSelections).toBe(true);
+    expect(criticalErrors).toEqual([]);
+  });
+});