feat: side-by-side columns shorthand (```columns fence)

Authors write a ```columns fenced block (columns separated by a line of
===); Pandoc passes the body through verbatim as <pre class="columns">,
and a new post-Pandoc transform in lib.wiki.expand_columns expands it
into a flex <div> of <poem> columns. Runs entirely Pi-side before the
MediaWiki API write — no wiki template or PHP extension required.

The transform lives in shared lib/wiki.py (called from markdown_to_wikitext),
so it is universal across all pipelines. Stdlib only; no new deps.

Docs: SCHEMA.md author contract + songs/root decision logs.
Also ignore __pycache__/.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

lib/wiki.py

@@ -1,6 +1,8 @@
 """Shared utilities for novoyuuparosk-auto-wiki pipelines."""
 
+import html
 import os
+import re
 import subprocess
 from urllib.parse import urlparse
 
@@ -8,6 +10,11 @@ import mwclient
 
 AUTO_BANNER_PREFIX = "{{Auto-generated"
 
+# A ```columns fenced block is passed through Pandoc verbatim as
+# <pre class="columns">…</pre>; columns within it are separated by a line of ===.
+_COLUMNS_BLOCK_RE = re.compile(r'<pre class="columns">(.*?)</pre>', re.DOTALL)
+_COLUMN_SEP_RE = re.compile(r"^\s*===\s*$", re.MULTILINE)
+
 
 def strip_first_h1(text: str) -> str:
     """Remove the first '# Heading' line and any immediately following blank line."""
@@ -21,6 +28,27 @@ def strip_first_h1(text: str) -> str:
     return "\n".join(lines)
 
 
+def expand_columns(wikitext: str) -> str:
+    """Expand ```columns fenced blocks into a flex row of <poem> columns.
+
+    Authors write a fenced code block tagged ``columns``; Pandoc passes its body
+    through verbatim as ``<pre class="columns">…</pre>`` (line breaks and blank
+    lines preserved, inline markup entity-escaped). Columns within the block are
+    separated by a line containing only ``===``. Each column is wrapped in
+    <poem> so its line breaks survive MediaWiki parsing, and content is
+    HTML-unescaped so inline markup written in the fence (e.g. <b>…</b>) renders
+    rather than appearing as literal text.
+    """
+
+    def render(match: re.Match) -> str:
+        body = html.unescape(match.group(1))
+        columns = _COLUMN_SEP_RE.split(body)
+        poems = "".join("<poem>\n" + col.strip("\n") + "\n</poem>" for col in columns)
+        return '<div style="display:flex; gap:3em; align-items:flex-start">' + poems + "</div>"
+
+    return _COLUMNS_BLOCK_RE.sub(render, wikitext)
+
+
 def markdown_to_wikitext(body: str) -> str:
     result = subprocess.run(
         ["pandoc", "-f", "markdown", "-t", "mediawiki"],
@@ -30,7 +58,7 @@ def markdown_to_wikitext(body: str) -> str:
     )
     if result.returncode != 0:
         raise RuntimeError(f"pandoc failed: {result.stderr.strip()}")
-    return result.stdout
+    return expand_columns(result.stdout)
 
 
 def connect_wiki() -> mwclient.Site: