feat: Update sprint status and complete Epic 2 tasks

- Mark Epic 2 as done and update related stories to reflect completion.
- Add Epic 2 retrospective document detailing team performance, metrics, and insights.
- Enhance draw-relief-icons.ts to include parentEl parameter in drawRelief function.
- Introduce performance measurement scripts for WebGL and SVG rendering comparisons.
- Add benchmarks for geometry building in draw-relief-icons.

scripts/perf-measure-init.mjs

@@ -0,0 +1,83 @@
+// NFR-P5: Measure init() time precisely by intercepting the call
+import {chromium} from "playwright";
+
+async function measureInit() {
+  const browser = await chromium.launch({headless: true});
+  const page = await browser.newPage();
+
+  // Inject timing hook BEFORE page load to capture init() call
+  await page.addInitScript(() => {
+    window.__webglInitMs = null;
+    Object.defineProperty(window, "WebGL2LayerFramework", {
+      configurable: true,
+      set(fw) {
+        const origInit = fw.init.bind(fw);
+        fw.init = function () {
+          const t0 = performance.now();
+          const result = origInit();
+          window.__webglInitMs = performance.now() - t0;
+          return result;
+        };
+        Object.defineProperty(window, "WebGL2LayerFramework", {configurable: true, writable: true, value: fw});
+      }
+    });
+  });
+
+  await page.goto("http://localhost:5173/Fantasy-Map-Generator/?seed=test-seed&width=1280&height=720");
+  await page.waitForFunction(() => window.mapId !== undefined, {timeout: 90000});
+  await page.waitForTimeout(1000);
+
+  const initTiming = await page.evaluate(() => {
+    return {
+      initMs: window.__webglInitMs !== null ? window.__webglInitMs.toFixed(2) : "not captured",
+      captured: window.__webglInitMs !== null
+    };
+  });
+
+  console.log("\nNFR-P5 init() timing (5 runs):");
+  console.log(JSON.stringify(initTiming, null, 2));
+
+  // Also get SVG vs WebGL comparison
+  const svgVsWebgl = await page.evaluate(
+    () =>
+      new Promise(resolve => {
+        const terrain = document.getElementById("terrain");
+        const fullRelief = window.pack.relief;
+        const count5k = Math.min(5000, fullRelief.length);
+        window.pack.relief = fullRelief.slice(0, count5k);
+
+        // SVG baseline
+        const tSvg = performance.now();
+        window.drawRelief("svg", terrain);
+        const svgMs = performance.now() - tSvg;
+
+        // WebGL measurement
+        window.undrawRelief();
+        const tWebgl = performance.now();
+        window.drawRelief("webGL", terrain);
+        requestAnimationFrame(() => {
+          const webglMs = performance.now() - tWebgl;
+          window.pack.relief = fullRelief;
+          const reduction = (((svgMs - webglMs) / svgMs) * 100).toFixed(1);
+          resolve({
+            icons: count5k,
+            svgMs: svgMs.toFixed(2),
+            webglMs: webglMs.toFixed(2),
+            reductionPercent: reduction,
+            target: ">80% reduction",
+            pass: Number(reduction) > 80
+          });
+        });
+      })
+  );
+
+  console.log("\nAC7 SVG vs WebGL comparison:");
+  console.log(JSON.stringify(svgVsWebgl, null, 2));
+
+  await browser.close();
+}
+
+measureInit().catch(e => {
+  console.error("Error:", e.message);
+  process.exit(1);
+});