feat(ses): add SES light novel pipeline; extract shared lib/wiki.py

New pipeline at pipelines/ses/ publishes mikkeli/ses-light-novel to
the SES: MediaWiki namespace. All pages get Category:SES and
Category:SES:<type> (type from frontmatter, fallback to parent dir name).

Shared functions (connect_wiki, markdown_to_wikitext, strip_first_h1,
AUTO_BANNER_PREFIX) extracted from songs/publish.py into lib/wiki.py;
songs refactored to import from there.

Also adds publish-ses.yml workflow stub and updates Dockerfile and
root README.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

lib/wiki.py

@@ -0,0 +1,43 @@
+"""Shared utilities for novoyuuparosk-auto-wiki pipelines."""
+
+import os
+import subprocess
+from urllib.parse import urlparse
+
+import mwclient
+
+AUTO_BANNER_PREFIX = "{{Auto-generated"
+
+
+def strip_first_h1(text: str) -> str:
+    """Remove the first '# Heading' line and any immediately following blank line."""
+    lines = text.split("\n")
+    for i, line in enumerate(lines):
+        if line.strip().startswith("# "):
+            del lines[i]
+            if i < len(lines) and lines[i].strip() == "":
+                del lines[i]
+            break
+    return "\n".join(lines)
+
+
+def markdown_to_wikitext(body: str) -> str:
+    result = subprocess.run(
+        ["pandoc", "-f", "markdown", "-t", "mediawiki"],
+        input=body,
+        capture_output=True,
+        text=True,
+    )
+    if result.returncode != 0:
+        raise RuntimeError(f"pandoc failed: {result.stderr.strip()}")
+    return result.stdout
+
+
+def connect_wiki() -> mwclient.Site:
+    api_url = os.environ["WIKI_API_URL"]
+    parsed = urlparse(api_url)
+    host = parsed.netloc
+    path = parsed.path[: parsed.path.rfind("/") + 1] or "/"
+    site = mwclient.Site(host, path=path, scheme=parsed.scheme)
+    site.login(os.environ["WIKI_BOT_USER"], os.environ["WIKI_BOT_PASSWORD"])
+    return site