Fix link URL formatting and fence blank-line collapse in Markdown converter

Claude-Session: https://claude.ai/code/session_01JtuZTCMW9TyogEmBgGf8JT

src/telegram/markdown.test.ts

@@ -54,4 +54,17 @@ describe("markdownToTelegramHtml", () => {
   it("collapses runs of blank lines and trims", () => {
     expect(markdownToTelegramHtml("\n\na\n\n\n\nb\n\n")).toBe("a\n\nb");
   });
+
+  it("protects URL from emphasis formatting (regression: __init__.py)", () => {
+    expect(markdownToTelegramHtml("See [the init file](https://github.com/org/repo/blob/main/__init__.py) for details")).toBe(
+      'See <a href="https://github.com/org/repo/blob/main/__init__.py">the init file</a> for details',
+    );
+  });
+
+  it("preserves blank lines inside fenced code blocks (regression: blank line collapse)", () => {
+    const md = "```python\ndef foo():\n\n  pass\n```";
+    expect(markdownToTelegramHtml(md)).toBe(
+      '<pre><code class="language-python">def foo():\n\n  pass</code></pre>',
+    );
+  });
 });