feat: ✨ enable the 3D viewer in the WASM port (WIP)

Builds KiCad's 3D viewer for the browser (opt in with BUILD_3D_VIEWER=ON) and
wires up the legacy-GL emulation it needs.

- build-kicad-target.sh / docker/build.sh: BUILD_3D_VIEWER →
  -DKICAD_BUILD_3D_VIEWER_WASM=ON + -sLEGACY_GL_EMULATION + the GL js-library.
- wasm/shims/gl_immediate_shim.js: display-list emulation (record/replay board
  layers), fixed-function + GLU stubs, throw-guards for unsupported pnames, and
  per-context GLImmediate init for the viewer's SECOND WebGL context.
- tests/kicad/3d-viewer.spec.ts + utils/pcbnew-ready.ts: open View → 3D Viewer.
- bumps the kicad submodule (EMSCRIPTEN-guarded GL changes).

WIP: the viewer window + UI render and geometry draws (glError=0x0), but the
board is not yet visibly rendered — GLImmediate's FFP shader program isn't
linked on the viewer's 2nd WebGL context. Full status + next steps in
features/feat/add-3d-view/notes.md.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

tests/kicad/utils/pcbnew-ready.ts

@@ -0,0 +1,47 @@
+import type { Page } from '@playwright/test';
+import { expect } from '../fixtures';
+import { clickByLabel } from '../../e2e/utils/element-tracker';
+
+/**
+ * Shared pcbnew bring-up helpers. Mirrors the bring-up sequence proven in
+ * load-pcb.spec.ts so multiple kicad specs (load-pcb, 3d-viewer, ...) can wait
+ * for a ready pcbnew the same way without duplicating the timing logic.
+ */
+
+/**
+ * KiCad first-run setup wizard. Click "Next >" until it's gone, then "Finish".
+ * If no wizard is present, both clicks no-op immediately.
+ */
+export async function dismissWizardIfPresent(page: Page): Promise<void> {
+    for (let i = 0; i < 12; i++) {
+        const advanced = await clickByLabel(page, 'Next >');
+        if (!advanced) break;
+        await page.waitForTimeout(400);
+    }
+    await clickByLabel(page, 'Finish');
+    await page.waitForTimeout(800);
+}
+
+/**
+ * Wait for pcbnew to boot: 2D canvas visible, element registry populated, the
+ * first-run wizard dismissed, and the main PcbFrame registered & visible.
+ */
+export async function waitForPcbnew(page: Page): Promise<void> {
+    await expect(page.locator('#canvas')).toBeVisible({ timeout: 90000 });
+    await page.waitForFunction(() => !!window.wxElementRegistry, null, { timeout: 90000 });
+    // Registry object ≠ app booted: wait for real UI entries (wizard or main
+    // frame) before dismissing — CI boots slower and the dismiss loop is bounded.
+    await page.waitForFunction(() => {
+        const registry = window.wxElementRegistry;
+        return !!registry && registry.findAll({}).length > 0;
+    }, null, { timeout: 150000 });
+    await page.waitForTimeout(2500);
+    await dismissWizardIfPresent(page);
+    await page.waitForFunction(() => {
+        const registry = window.wxElementRegistry;
+        if (!registry) return false;
+        return registry.findAll({ visible: true })
+            .some((el) => el.name === 'PcbFrame');
+    }, null, { timeout: 90000 });
+    await page.waitForTimeout(1500);
+}