F10 SLICE-2: fix renderReview author-coloring for duplicate blocks; tidy renderReviewOp + escape proposal id (#29)

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

test/trackChangesModel.test.ts

@@ -295,6 +295,18 @@ describe("renderReview", () => {
     expect(html).toContain("mermaid");
     expect(html).not.toContain("cw-by-");
   });
+  test("renderReview: author-colors the correct block when two paragraphs are identical", () => {
+    // Two identical paragraphs; baseline has only the first, so the SECOND is an
+    // added block authored by human. Its span must color THAT block, not the first.
+    const baseline = "Hello world";
+    const current = "Hello world\n\nHello world";
+    // second "Hello world" starts at offset 13; "world" at 19..24
+    const spans = [{ start: 19, end: 24, author: "human" as const }];
+    const html = renderReview(baseline, current, spans, []);
+    // exactly one cw-by-human span (the added second block's "world"), not zero, not on the first.
+    const count = (html.match(/cw-by-human/g) ?? []).length;
+    expect(count).toBe(1);
+  });
 });
 
 import { renderTrackChanges as rtc2 } from "../src/trackChangesModel";