Generated-code hygiene: listener cleanup, shared cn(), whitespace collapse, probe stripping, sub-pixel snapping, clone-origin metadata, dependency pinning

- DittoWire/Accordion/DropdownMenu runtime templates: AbortController-based
  listener cleanup, idempotent effects, orphan panel removal on unmount
- Emit a single src/lib/utils.ts cn() instead of a copy per component file
- Collapse captured whitespace runs under white-space:normal (pre* preserved)
- Tag source-injected font-metric probe nodes at capture; drop them from IR
- Snap sub-pixel arbitrary lengths (integer within 0.1px, else 1 decimal)
- Emit SITE_ORIGIN (src/lib/site.ts, env-overridable): sitemap/robots/
  canonical/og:url/JSON-LD resolve against the clone's own origin instead of
  the source domain
- Pin lottie-web in generated package.json whenever DittoLottie is emitted

144 tests pass (21 new), typecheck clean.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

compiler/test/irPrune.test.ts

@@ -98,3 +98,21 @@ describe("IR prune keeps <source> media candidates", () => {
     assert.equal(findByTag(root, "picture"), null);
   });
 });
+
+describe("IR drops font-metric probe nodes (fix 4)", () => {
+  it("excludes a walker-tagged probe node from the IR, keeping its siblings", () => {
+    const probe: RawNode = {
+      ...raw("div", { class: "font-probe" }, [{ text: "Mgy" }]),
+      probe: true,
+    };
+    const real = raw("h1", { class: "title" }, [{ text: "Heading" }]);
+    const body = raw("body", {}, [real, probe]);
+
+    const root = buildFixtureIR(body);
+
+    const kept = root.children.filter((c) => !isTextChild(c)).map((c) => (c as IRNode).tag);
+    assert.deepEqual(kept, ["h1"], "probe div is dropped, the real heading survives");
+    // Its text must not leak into the tree either.
+    assert.equal(findByTag(root, "div"), null);
+  });
+});