fix(markdown): remove table double-header + add imgui_md bullet workaround

Table fix (src/markdown_table.py):
- Add TableColumnFlags_.width_stretch to each table_setup_column call
  (was missing — columns had no width to wrap against, so text_wrapped
  couldn't grow row height → all rows squished together)
- Remove the explicit for-h-in-headers: table_next_column + text_wrapped(h)
  loop. table_headers_row() already renders the header from the
  table_setup_column() names; the explicit loop was drawing it AGAIN on
  top → double-rendered header rows.

Bullet fix (src/markdown_helper.py):
- Revert _render_md_no_bullet_overlap → simple imgui_md.render(chunk);
  imgui.spacing() (the original af0bbe97 approach). The complex
  workaround was stripping '- ' and rendering stripped text to imgui_md,
  which double-rendered '- 1. ...' content (imgui.bullet from my code +
  numbered list marker from imgui_md).
- Add MarkdownRenderer._normalize_bullet_delimiters: regex-converts
  '* ' markers to '- ' before passing to imgui_md. This works around
  the upstream bug in mekhontsev/imgui_md BLOCK_LI where the '*' case
  calls ImGui::Bullet() without ImGui::SameLine(), causing the bullet
  to render on its own Y with the text on the next Y. The '-' case
  uses Text+SameLine which is correct. Cannot fix from Python (we
  can't subclass the C++ class) — pre-conversion is the cheapest fix.

Tests:
- test_markdown_table_wrapped.py: updated to assert new behavior
  (text_wrapped count == cell count, not header+cell).
- test_markdown_table_columns.py: updated to assert exactly 6
  table_next_column calls (cells only, not 9).
- test_markdown_helper_bullets.py: rewrote for new public-API behavior
  (imgui_md.render called with the unstripped chunk).

16/16 markdown unit tests pass.

src/markdown_helper.py

@@ -114,8 +114,8 @@ class MarkdownRenderer:
   """
   if not text:
    return
-
   from src.markdown_table import parse_tables, render_table
+  text = self._normalize_bullet_delimiters(text)
   blocks = parse_tables(text)
   lines = text.splitlines(keepends=True)
   if not lines:
@@ -134,7 +134,8 @@ class MarkdownRenderer:
    if md_buf:
     chunk = "".join(md_buf)
     if chunk:
-     self._render_md_no_bullet_overlap(chunk)
+     imgui_md.render(chunk)
+     imgui.spacing()
     md_buf.clear()
 
   def flush_code() -> None:
@@ -188,51 +189,19 @@ class MarkdownRenderer:
   flush_md()
   flush_code()
 
- def _render_md_no_bullet_overlap(self, chunk: str) -> None:
-  """Render markdown, but split out bulleted-list sections and render them
-  as plain text via imgui.text to avoid imgui_md's known bullet-overlap bug.
-  """
-  import re
-  list_pattern = re.compile(r"^(?P<indent>[ \t]*)(?:[-*+])\s+", re.MULTILINE)
-  current_pos = 0
-  for m in list_pattern.finditer(chunk):
-   if m.start() > current_pos:
-    pre = chunk[current_pos:m.start()]
-    if pre: imgui_md.render(pre)
-   list_start = m.start()
-   indent_len = len(m.group("indent"))
-   i = list_start
-   while i < len(chunk):
-    line_end = chunk.find("\n", i)
-    if line_end == -1: line_end = len(chunk)
-    line = chunk[i:line_end]
-    stripped = line.lstrip(" \t")
-    leading_ws = len(line) - len(stripped)
-    if leading_ws == indent_len and (stripped.startswith(("- ", "* ", "+ ")) or stripped == ""):
-     i = line_end + 1
-     continue
-    if leading_ws < indent_len:
-     break
-    i = line_end + 1
-   list_block = chunk[list_start:i]
-   for line in list_block.splitlines():
-    if not line.strip():
-     imgui.spacing()
-     continue
-    stripped = line.lstrip(" \t")
-    indent = len(line) - len(stripped)
-    if stripped.startswith(("- ", "* ", "+ ")):
-     imgui.bullet()
-     imgui.same_line()
-     imgui_md.render(stripped[2:])
-    else:
-     if indent > 0: imgui.indent(indent * 2)
-     imgui_md.render(stripped)
-     if indent > 0: imgui.unindent(indent * 2)
-   current_pos = i
-  if current_pos < len(chunk):
-   tail = chunk[current_pos:]
-   if tail: imgui_md.render(tail)
+ def _normalize_bullet_delimiters(self, text: str) -> str:
+   """Convert '*' list markers to '-' before passing to imgui_md.
+
+   Upstream imgui_md (mekhontsev/imgui_md) has a rendering bug in BLOCK_LI
+   for the '*' delimiter: it calls ImGui::Bullet() without ImGui::SameLine(),
+   causing the bullet to render on its own Y position with the text on the
+   next Y. The '-' delimiter uses Text+SameLine which works correctly.
+   Converting '* ' to '- ' is the cheapest workaround available from Python
+   (we cannot subclass the C++ imgui_md class).
+   [C: src/markdown_helper.py:MarkdownRenderer.render]
+   """
+   import re
+   return re.sub(r"(?m)^([ \t]*)\*[ \t]+", r"\1- ", text)
 
  def render_unindented(self, text: str) -> None:
   """Render Markdown text with automatic unindentation."""

src/markdown_table.py

@@ -13,11 +13,8 @@ def render_table(block: "TableBlock") -> None:
  flags = imgui.TableFlags_.borders | imgui.TableFlags_.row_bg | imgui.TableFlags_.resizable
  if not imgui.begin_table("md_table", n_cols, flags): return
  for h in block.headers:
-  imgui.table_setup_column(h)
+  imgui.table_setup_column(h, imgui.TableColumnFlags_.width_stretch)
  imgui.table_headers_row()
- for h in block.headers:
-  imgui.table_next_column()
-  imgui.text_wrapped(h)
  for row in block.rows:
   imgui.table_next_row()
   for c in row: