fix(editor): the white screen was React unmounting its own crash reporter

All three prod crash cascades (v0.1.19–21) ended white for the same reason:
the final trap lands inside a child's EFFECT (an embind call reached through
a react-query subscription), React unmounts the entire root, and the fatal
overlay + console panel die with the tree they were built to survive.

- WasmErrorBoundary: crash-capable children live inside it; the fatal screen
  and the console panel live OUTSIDE and keep rendering. WasmTool state
  (logs included) survives a descendant render/effect throw.
- The fatal screen is now an actual blue screen (:( + solid blue), and every
  promotion path (window error, unhandled rejection, worker error, boundary)
  auto-opens the console — the log is the only account of what was loading.
- tests/web/fatal-overlay.spec.ts pins the contract: a terminal uncaught
  error after boot ⇒ visible fatal overlay + open console with the [fatal]
  record. Green locally (23.9s).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_019SE4o46Lnq3hF574FFq8x4

tests/web/fatal-overlay.spec.ts

@@ -0,0 +1,52 @@
+import { test, expect } from '@playwright/test';
+
+/**
+ * The blue screen of death must actually appear (WSOD hardening, async/16
+ * companion). Three prod crash reports in a row (v0.1.19–21) ended in a WHITE
+ * page because the crash killed the very UI built to report it: the final
+ * trap landed inside a React effect, React unmounted the root, and the fatal
+ * overlay + console panel died with it. The fix is layered — window/worker
+ * error listeners promote a `fatal` state rendered OUTSIDE a WasmErrorBoundary
+ * that absorbs descendant render/effect throws — and this spec pins the
+ * user-visible contract:
+ *
+ *   a terminal-looking uncaught error after boot ⇒ the blue fatal overlay is
+ *   VISIBLE and the console log panel is OPEN (the log is the only account of
+ *   what was loading; a collapsed console behind a mystery screen is useless).
+ *
+ * The throw is synthesized (a real wasm trap is not deterministically
+ * available), but it exercises the identical promotion path: uncaught error →
+ * terminal() match → promote → overlay + console.
+ */
+
+const SCOPE = 'default';
+
+test('a terminal uncaught error raises the blue fatal overlay with the console open', async ({
+  page,
+}) => {
+  test.setTimeout(300000); // one full pcbnew wasm boot
+
+  await page.goto(`/${SCOPE}/projects/demo/demo.kicad_pcb?user=fatal-probe`);
+  await expect(page.locator('#canvas')).toBeVisible({ timeout: 120000 });
+  await expect
+    .poll(() => page.title(), {
+      message: 'editor never reached the expected title',
+      timeout: 120000,
+      intervals: [1000],
+    })
+    .toMatch(/demo — PCB Editor/i);
+
+  // Synthesize the trap: an uncaught error whose message matches the
+  // terminal signature set (Firefox's bare wasm trap spelling included).
+  await page.evaluate(() => {
+    setTimeout(() => {
+      throw new Error('index out of bounds');
+    }, 0);
+  });
+
+  await expect(page.getByTestId('fatal-overlay')).toBeVisible({ timeout: 10000 });
+  // The console panel auto-opened and carries the promotion record.
+  await expect(page.locator('pre').filter({ hasText: '[fatal]' })).toBeVisible({
+    timeout: 10000,
+  });
+});