feat(telegram): add overflow split mode (#101)

tests/test_rendering.py

@@ -1,4 +1,4 @@
-from takopi.telegram.render import render_markdown
+from takopi.telegram.render import render_markdown, split_markdown_body
 
 
 def test_render_markdown_basic_entities() -> None:
@@ -18,3 +18,13 @@ def test_render_markdown_code_fence_language_is_string() -> None:
     assert entities is not None
     assert any(e.get("type") == "pre" and e.get("language") == "py" for e in entities)
     assert any(e.get("type") == "code" for e in entities)
+
+
+def test_split_markdown_body_closes_and_reopens_fence() -> None:
+    body = "```py\n" + ("line\n" * 10) + "```\n\npost"
+
+    chunks = split_markdown_body(body, max_chars=40)
+
+    assert len(chunks) > 1
+    assert chunks[0].rstrip().endswith("```")
+    assert chunks[1].startswith("```py\n")