feat(places): submit place and outcode sitemaps

Separate children per family so Search Console reports the location layer's
indexation apart from the school pages' — which is the point of the index
built in W1, and the number the stop condition watches.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_015mWQnpye9F299NVRCCSRvj

backend/app.py

@@ -194,6 +194,29 @@ def _urlset(rows: list[str]) -> str:
     ])
 
 
+def _place_url(place) -> str:
+    """The canonical path for a place. Two namespaces, per the spec.
+
+    Towns and localities share /schools/[place]; authorities take their own
+    prefix because 67 town names collide with an authority name and neither
+    set contains the other.
+    """
+    if place.kind == "authority":
+        return f"/schools/authority/{place.slug}"
+    if place.kind == "outcode":
+        return f"/schools/near/{place.slug}"
+    return f"/schools/{place.slug}"
+
+
+def _place_sitemap_rows(kinds: tuple[str, ...]) -> list[str]:
+    return [
+        _url_element(BASE_URL + _place_url(p))
+        for p in sorted(get_place_registry().values(),
+                        key=lambda p: (p.kind, p.slug))
+        if p.kind in kinds
+    ]
+
+
 def build_sitemaps() -> dict[str, str]:
     """Build the sitemap index and every child, keyed by name."""
     df = load_school_data()
@@ -211,6 +234,17 @@ def build_sitemaps() -> dict[str, str]:
     for n, chunk in enumerate(chunks, start=1):
         children[f"schools-{n}.xml"] = _urlset(chunk)
 
+    # Separate children per family: Search Console reports coverage per
+    # submitted sitemap, which is how the location layer's indexation is
+    # measured apart from the school pages'.
+    for label, kinds in (("places", ("town", "locality", "authority")),
+                         ("outcodes", ("outcode",))):
+        rows = _place_sitemap_rows(kinds)
+        chunks = [rows[i:i + SITEMAP_CHUNK_SIZE]
+                  for i in range(0, len(rows), SITEMAP_CHUNK_SIZE)] or [[]]
+        for n, chunk in enumerate(chunks, start=1):
+            children[f"{label}-{n}.xml"] = _urlset(chunk)
+
     # On a sitemap index, lastmod means "when this sitemap file last changed",
     # so generation time is the correct value here — unlike on a <url>, where
     # it would be a claim about content we cannot support.