fix(wasm): self-heal fiber trampoline so schematic load doesn't hang

The emscripten fiber glue gates Fibers.trampoline() on Fibers.trampolineRunning
and resets it at the end of its loop. At startup emscripten_set_main_loop(...,1)
throws "unwind" to establish the main loop, and KiCad does so from inside a tool
coroutine, so the throw propagates THROUGH the trampoline and skips the reset —
leaving the flag stuck true. Every fiber swap after startup then becomes a silent
no-op, so opening a schematic (SetScreen -> RunAction(selectionClear) -> fiber
swap) hangs forever with the editor stuck on "untitled".

Wrap the trampoline loop in try/finally (inject-dyncall-shims.sh section "3c") so
the flag is always reset. Add tests/kicad/eeschema-load.spec.ts, which opens a
small wires/junctions schematic via Module.kicadOpenFile and asserts the editor
title switches away from "untitled": it times out (RED) without the shim and
passes (GREEN) with it. Also add features/web-init/0002-url-regex-modal-followup.md
capturing the unrelated URL-detection wxRegEx modal surfaced once loading works.

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

tests/kicad/eeschema-load.spec.ts

@@ -0,0 +1,138 @@
+import { test, expect } from './fixtures';
+
+/**
+ * Eeschema schematic-LOAD regression test (fiber / Asyncify trampoline shim).
+ *
+ * This guards the fix in scripts/common/inject-dyncall-shims.sh
+ * ("3c. Fiber trampoline self-heal").
+ *
+ * Background: KiCad's tool framework runs action handlers in coroutines that
+ * switch stacks via emscripten_fiber_swap. The emscripten fiber glue gates its
+ * context switch on `Fibers.trampolineRunning` and resets that flag at the end of
+ * `Fibers.trampoline()`. At startup `emscripten_set_main_loop(...,1)` throws
+ * "unwind" to establish the main loop; KiCad does that from inside a tool
+ * coroutine, so the throw propagates THROUGH the trampoline and skips the reset.
+ * The flag then stays `true` forever, `Fibers.trampoline()` becomes a permanent
+ * no-op, and EVERY fiber swap after startup silently fails to switch contexts.
+ *
+ * Opening a schematic calls SCH_EDIT_FRAME::SetScreen() ->
+ * m_toolManager->RunAction(selectionClear), which performs such a fiber swap. So
+ * without the shim, OpenProjectFiles() suspends in selectionClear and never
+ * resumes: the load hangs and the editor title stays "untitled".
+ *
+ * The shim wraps the trampoline loop in try/finally so the flag is always reset.
+ * With it, the load completes and the title switches to the opened file.
+ *
+ * Assertion strategy: open a minimal (text-free) schematic via the programmatic
+ * Module.kicadOpenFile() hook and poll the editor title. GREEN once it shows the
+ * file name; RED (poll timeout) if the load hangs because the shim is missing.
+ *
+ * The schematic holds a few wires + junctions (a box with a crossbar) so a dev
+ * can eyeball a screenshot and immediately see whether it rendered. It uses ONLY
+ * geometry — no text/symbol fields — both to keep the visual unambiguous and to
+ * avoid an unrelated, still-open URL-detection wxRegEx bug that pops a modal when
+ * text is rendered (see the regex follow-up). version 20250114 is within this
+ * build's supported schematic version (SEXPR_SCHEMATIC_FILE_VERSION 20251012).
+ */
+
+const SAMPLE_SCH = `(kicad_sch
+\t(version 20250114)
+\t(generator "eeschema")
+\t(generator_version "9.0")
+\t(uuid "11111111-1111-1111-1111-111111111111")
+\t(paper "A4")
+\t(lib_symbols)
+\t(wire (pts (xy 50.8 50.8) (xy 101.6 50.8)) (stroke (width 0) (type default)) (uuid "22222222-0000-0000-0000-000000000001"))
+\t(wire (pts (xy 50.8 101.6) (xy 101.6 101.6)) (stroke (width 0) (type default)) (uuid "22222222-0000-0000-0000-000000000002"))
+\t(wire (pts (xy 50.8 50.8) (xy 50.8 101.6)) (stroke (width 0) (type default)) (uuid "22222222-0000-0000-0000-000000000003"))
+\t(wire (pts (xy 101.6 50.8) (xy 101.6 101.6)) (stroke (width 0) (type default)) (uuid "22222222-0000-0000-0000-000000000004"))
+\t(wire (pts (xy 50.8 76.2) (xy 101.6 76.2)) (stroke (width 0) (type default)) (uuid "22222222-0000-0000-0000-000000000005"))
+\t(junction (at 50.8 76.2) (diameter 1.016) (color 0 0 0 0) (uuid "33333333-0000-0000-0000-000000000001"))
+\t(junction (at 101.6 76.2) (diameter 1.016) (color 0 0 0 0) (uuid "33333333-0000-0000-0000-000000000002"))
+\t(sheet_instances
+\t\t(path "/"
+\t\t\t(page "1")
+\t\t)
+\t)
+)
+`;
+
+type EmscriptenFS = {
+    mkdirTree(path: string): void;
+    writeFile(path: string, data: string): void;
+};
+type KicadModule = { kicadOpenFile(path: string): unknown };
+
+test.describe('Eeschema schematic load', () => {
+    test('opens a .kicad_sch via kicadOpenFile and finishes loading (fiber shim regression)', async ({
+        page,
+    }) => {
+        await page.goto('/kicad/eeschema.html');
+
+        // Editor must be fully up before we drive the open: a visible canvas, the
+        // wx element registry, the embind open hook, and a top-level Frame (so
+        // kicadOpenFile's GetTopWindow() resolves to the editor, not a wizard).
+        await expect(page.locator('#canvas')).toBeVisible({ timeout: 90000 });
+        await page.waitForFunction(() => !!window.wxElementRegistry, null, { timeout: 90000 });
+        await page.waitForFunction(
+            () =>
+                typeof (window as unknown as { Module?: KicadModule }).Module?.kicadOpenFile ===
+                'function',
+            null,
+            { timeout: 90000 }
+        );
+        await page.waitForFunction(
+            () =>
+                !!window.wxElementRegistry &&
+                window.wxElementRegistry
+                    .findAll({ visible: true })
+                    .some((e) => /Frame$/.test(e.typeName) || (e.name || '').endsWith('Frame')),
+            null,
+            { timeout: 90000 }
+        );
+
+        // Sanity: editor starts on an untitled schematic.
+        expect(await page.title()).toMatch(/untitled/i);
+
+        // Write a minimal, version-compatible schematic into MEMFS and open it.
+        // kicadOpenFile runs OpenProjectFiles under Asyncify: it suspends and
+        // returns a placeholder, so we ignore the return and poll the title.
+        const openedPath = await page.evaluate((content) => {
+            const w = window as unknown as { FS: EmscriptenFS; Module: KicadModule };
+            const dir = '/home/kicad/documents';
+            try {
+                w.FS.mkdirTree(dir);
+            } catch {
+                /* already exists */
+            }
+            const path = `${dir}/regression.kicad_sch`;
+            w.FS.writeFile(path, content);
+            w.Module.kicadOpenFile(path);
+            return path;
+        }, SAMPLE_SCH);
+        expect(openedPath).toContain('regression.kicad_sch');
+
+        // With the fiber trampoline self-heal shim the load completes and the
+        // title switches to the opened file. WITHOUT it, the selectionClear fiber
+        // swap hangs and the title stays "untitled" -> this poll times out (RED).
+        await expect
+            .poll(async () => page.title(), {
+                message:
+                    'Schematic load did not complete (title stayed "untitled"). ' +
+                    'The fiber trampoline self-heal shim (inject-dyncall-shims.sh "3c") is ' +
+                    'likely missing or broken.',
+                timeout: 30000,
+                intervals: [500],
+            })
+            .toMatch(/regression/i);
+
+        // Give the canvas a moment to paint the loaded geometry, then capture a
+        // screenshot so a dev can eyeball the rendered wires/junctions (box with
+        // a crossbar) as a quick "is it working?" check.
+        await page.waitForTimeout(1000);
+        await page.screenshot({
+            path: 'test-results/eeschema-load-rendered.png',
+            scale: 'device',
+        });
+    });
+});