fix(mkdocs): rebase cross-kind wiki links under directory URLs

Wiki pages linking to a sibling kind (for example ../lib/...) were emitted verbatim by MkDocs and, with use_directory_urls, resolved into a non-existent <kind>/<kind>/ path. Add a docforge-linkfix plugin (doc-forge 0.0.8) that rebases those links to the repository root.

tests/cli/test_mkdocs_links.py

@@ -0,0 +1,55 @@
+from types import SimpleNamespace
+
+from docforge.mkdocs_links import LinkFixPlugin
+
+
+def _page(dest_uri: str):
+    return SimpleNamespace(file=SimpleNamespace(dest_uri=dest_uri))
+
+
+def _fix(markdown: str, dest_uri: str) -> str:
+    return LinkFixPlugin().on_page_markdown(
+        markdown,
+        page=_page(dest_uri),
+        config=SimpleNamespace(),
+        files=SimpleNamespace(),
+    )
+
+
+def test_root_page_keeps_single_parent():
+    src = "[lib](../lib/pkg/index.md)"
+    assert _fix(src, "index.html") == src
+
+
+def test_nested_page_adds_directory_depth():
+    assert _fix("[lib](../lib/pkg/index.md)", "01_overview/index.html") == (
+        "[lib](../../lib/pkg/index.md)"
+    )
+
+
+def test_deeply_nested_page_adds_two_levels():
+    src = "[lib](../lib/pkg/index.md)"
+    got = _fix(src, "04_development/02_releasing/index.html")
+    assert got == "[lib](../../../lib/pkg/index.md)"
+
+
+def test_multiple_cross_kind_links_are_rebased():
+    src = "See [a](../lib/a) and [b](../api/b)."
+    got = _fix(src, "01_overview/index.html")
+    assert got == "See [a](../../lib/a) and [b](../../api/b)."
+
+
+def test_wiki_kind_is_rebased():
+    assert _fix("[w](../wiki/index.md)", "01_overview/index.html") == (
+        "[w](../../wiki/index.md)"
+    )
+
+
+def test_relative_within_kind_untouched():
+    src = "[next](02_install.md) and [prev](../index.md)"
+    assert _fix(src, "01_overview/index.html") == src
+
+
+def test_absolute_and_url_links_untouched():
+    src = "[site](https://example.com/lib/x) and [root](/lib/x) and [r](lib/x)"
+    assert _fix(src, "a/index.html") == src