feat: rank console pages above setup lists

A setup's list for one console is a reference page kept out of the
search index, naming its setup as parent. System pages carry file names
and the platforms' own ids as attribute search fields, never as text.
Arcade gets its own sidebar group.

scripts/sitestarlight.py

@@ -368,6 +368,17 @@ def split_title(markdown: str) -> tuple[str, str, str]:
 _CARD_NAME = re.compile(r'<h3[^>]*class="rb-file-title"(?![^>]*data-pagefind-ignore)[^>]*><code>([^<]+)</code>')
 
 
+def search_field(key: str, words: list[str]) -> str:
+    """A search field of the page, held in an attribute of an empty
+    element: the text of an element is indexed and shown as the result's
+    excerpt (a run of 250 file names). Pagefind splits several fields at a
+    comma, so a value carries none."""
+    value = " ".join(word.replace(",", " ") for word in words).strip()
+    if not value:
+        return ""
+    return f'\n<span data-pagefind-meta="{html.escape(f"{key}:{value}", quote=True)}" hidden></span>\n'
+
+
 def file_names_meta(body: str) -> str:
     """The names of the files a system page holds cards for, as a search
     field of the page. A page of 250 cards is long, and the search weighs a
@@ -375,9 +386,35 @@ def file_names_meta(body: str) -> str:
     after every short page citing the name. The field is weighted in the
     site's ranking (astro.config.mjs, metaWeights.files)."""
     names = sorted({unescape(name) for name in _CARD_NAME.findall(body)})
-    if not names:
-        return ""
-    return f'\n<span data-pagefind-meta="files" hidden>{html.escape(" ".join(names))}</span>\n'
+    return search_field("files", names)
+
+
+# systems/ page -> the platforms' own ids for the consoles it holds, built
+# on the first system page, once the generator has installed the sections.
+_page_aliases: dict[str, list[str]] = {}
+_page_aliases_built = [False]
+
+
+def page_aliases(rel: str) -> list[str]:
+    """The names the platforms file the consoles of a system page under
+    (psx, dreamcast, gba), from siterender.system_search_aliases(): "psx
+    bios" finds the PlayStation page though the page never says psx."""
+    if not _page_aliases_built[0]:
+        import siterender
+
+        by_page: dict[str, set[str]] = {}
+        for sys_id in list(siterender._system_page_map):
+            section = siterender.system_section(sys_id)
+            names = siterender.system_search_aliases(sys_id)
+            if not section or not names:
+                continue
+            target = siterender.console_href(*section).partition("#")[0]
+            by_page.setdefault(urllib.parse.unquote(target), set()).update(names)
+        _page_aliases.clear()
+        _page_aliases.update({page: sorted(names, key=str.casefold)
+                              for page, names in by_page.items()})
+        _page_aliases_built[0] = bool(siterender._system_page_map)
+    return list(_page_aliases.get(rel, []))
 
 
 _NEXT_STEPS = re.compile(r"^## Next steps\b[^\n]*\n+(?P<list>(?:[ \t]*[-*] .*\n?)+)", re.M)
@@ -407,9 +444,12 @@ def finalize_page(
     terms: dict[str, str],
     search: bool = True,
     logo: str = "",
+    parent: dict | None = None,
 ) -> tuple[str, str]:
     """The Starlight file for a page body: its path under the content
-    collection and its text."""
+    collection and its text. *parent* ({label, link}, the link written
+    relative to the page) is the page a part page belongs to: the route
+    middleware makes it the last crumb and marks it in the sidebar."""
     title, title_id, body = split_title(markdown)
     body = body.lstrip("\n")
     body = rewrite_links(body, rel)
@@ -427,7 +467,7 @@ def finalize_page(
     body = re.sub(r'<span class="(rb-badge(?![^"]*rb-badge-archive)[^"]*)"',
                   r'<span data-pagefind-ignore class="\1"', body)
     if rel.startswith("systems/"):
-        body += file_names_meta(body)
+        body += file_names_meta(body) + search_field("aliases", page_aliases(rel))
     components = used_components(body)
     stem = rel.rsplit(".", 1)[0]
     if components:
@@ -449,6 +489,9 @@ def finalize_page(
         front["level"] = level
     if logo:
         front["logo"] = logo
+    if parent:
+        front["parent"] = {"label": str(parent["label"]),
+                           "link": resolve(rel, str(parent["link"]))}
     if weight:
         front["searchWeight"] = weight
     if rel == NOT_FOUND: