fix(chat): render a markdown table that follows prose with no blank line (#83)

The chat renderer's paragraph collector never stopped at a table header,
so a table right after a line of text was shown as raw pipes. A table now
interrupts a paragraph as in GFM, and the divider accepts single dashes.

Closes #83

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

client/src/components/conversation/__tests__/MarkdownContent.test.tsx

@@ -153,4 +153,18 @@ describe("<MarkdownContent />", () => {
     expect(container.firstChild).not.toBeNull();
     expect(container.querySelectorAll("p, ul, ol, blockquote, pre, hr").length).toBe(0);
   });
+
+  it("renders a table that follows prose with no blank line (issue #83)", () => {
+    const text = 'Cách kiểm tra:\n| Token xoá | Số chỗ |\n|---|---|\n| `width="N"` | 29 |';
+    const { container } = render(<MarkdownContent text={text} />);
+    expect(container.querySelector("p")?.textContent).toBe("Cách kiểm tra:");
+    expect(container.querySelectorAll("th").length).toBe(2);
+    expect(container.querySelectorAll("tbody tr").length).toBe(1);
+    expect(container.textContent).not.toContain("|---|");
+  });
+
+  it("accepts a GFM divider with single dashes", () => {
+    const { container } = render(<MarkdownContent text={"| a | b |\n|-|:-:|\n| 1 | 2 |"} />);
+    expect(container.querySelectorAll("th").length).toBe(2);
+  });
 });