feat(telegram): convert markdown tables to bullet points (#1495)

Tables render poorly in Telegram (pipes stripped, whitespace collapses).
This adds a 'tableMode' option to markdownToIR that converts tables to
nested bullet points, which render cleanly on mobile.

- Add tableMode: 'flat' | 'bullets' to MarkdownParseOptions
- Track table state during token rendering
- Render tables as bullet points with first column as row labels
- Apply bold styling to row labels for visual hierarchy
- Enable tableMode: 'bullets' for Telegram formatter

Closes #TBD

src/markdown/ir.table-bullets.test.ts

@@ -0,0 +1,91 @@
+import { describe, expect, it } from "vitest";
+import { markdownToIR } from "./ir.js";
+
+describe("markdownToIR tableMode bullets", () => {
+  it("converts simple table to bullets", () => {
+    const md = `
+| Name | Value |
+|------|-------|
+| A    | 1     |
+| B    | 2     |
+`.trim();
+
+    const ir = markdownToIR(md, { tableMode: "bullets" });
+    
+    // Should contain bullet points with header:value format
+    expect(ir.text).toContain("• Value: 1");
+    expect(ir.text).toContain("• Value: 2");
+    // Should use first column as labels
+    expect(ir.text).toContain("A");
+    expect(ir.text).toContain("B");
+  });
+
+  it("handles table with multiple columns", () => {
+    const md = `
+| Feature | SQLite | Postgres |
+|---------|--------|----------|
+| Speed   | Fast   | Medium   |
+| Scale   | Small  | Large    |
+`.trim();
+
+    const ir = markdownToIR(md, { tableMode: "bullets" });
+    
+    // First column becomes row label
+    expect(ir.text).toContain("Speed");
+    expect(ir.text).toContain("Scale");
+    // Other columns become bullet points
+    expect(ir.text).toContain("• SQLite: Fast");
+    expect(ir.text).toContain("• Postgres: Medium");
+    expect(ir.text).toContain("• SQLite: Small");
+    expect(ir.text).toContain("• Postgres: Large");
+  });
+
+  it("preserves flat mode as default", () => {
+    const md = `
+| A | B |
+|---|---|
+| 1 | 2 |
+`.trim();
+
+    const ir = markdownToIR(md); // default is flat
+    
+    // Flat mode uses tabs
+    expect(ir.text).toContain("A");
+    expect(ir.text).toContain("B");
+    expect(ir.text).toContain("1");
+    expect(ir.text).toContain("2");
+    // Should not have bullet formatting
+    expect(ir.text).not.toContain("•");
+  });
+
+  it("handles empty cells gracefully", () => {
+    const md = `
+| Name | Value |
+|------|-------|
+| A    |       |
+| B    | 2     |
+`.trim();
+
+    const ir = markdownToIR(md, { tableMode: "bullets" });
+    
+    // Should handle empty cell without crashing
+    expect(ir.text).toContain("B");
+    expect(ir.text).toContain("• Value: 2");
+  });
+
+  it("bolds row labels in bullets mode", () => {
+    const md = `
+| Name | Value |
+|------|-------|
+| Row1 | Data1 |
+`.trim();
+
+    const ir = markdownToIR(md, { tableMode: "bullets" });
+    
+    // Should have bold style for row label
+    const hasRowLabelBold = ir.styles.some(
+      (s) => s.style === "bold" && ir.text.slice(s.start, s.end) === "Row1"
+    );
+    expect(hasRowLabelBold).toBe(true);
+  });
+});