refactor: rename similar → nearby, so the code says what the section does

The section ranks on distance and is headed "Other schools nearby", but every
identifier still called it "similar" — the exact drift that leaves a later
reader trusting a name over the behaviour.

Mechanical: files, the module, the payload key, the type, the components, the
prop. No behaviour change; the suites are unchanged in count and still green.
Free to do now because #150 has not merged, so the payload key rename needs no
lockstep deploy. Uses of "similar" that are ordinary English — progress
measures compared to similar pupils, and unrelated comments — are untouched.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

backend/app.py

@@ -41,7 +41,7 @@ from .data_loader import get_data_info as get_db_info
 from . import flags
 from .places import build_place_index, build_place_registry, places_for_urn
 from .schemas import METRIC_DEFINITIONS, PHASE_GROUPS, RANKING_COLUMNS, SCHOOL_COLUMNS
-from .similar_schools import select_similar
+from .nearby_schools import select_nearby
 from .utils import clean_for_json, convert_to_native
 
 # Values to exclude from filter dropdowns (empty strings, non-applicable labels)
@@ -266,10 +266,10 @@ def _places_payload(urn: int) -> list[dict]:
     return payload
 
 
-def _similar_schools_payload(urn: int) -> list[dict]:
+def _nearby_schools_payload(urn: int) -> list[dict]:
     """The nearest eligible schools this page may offer, closest first.
 
-    Phase and reach are read from the school's own row inside select_similar,
+    Phase and reach are read from the school's own row inside select_nearby,
     so nothing here can hand it a phase that disagrees with the data.
 
     Wrapped: a failure in selection must never 500 a page that is otherwise
@@ -277,12 +277,12 @@ def _similar_schools_payload(urn: int) -> list[dict]:
     section simply does not render.
     """
     try:
-        return select_similar(load_latest_school_data(), int(urn))
+        return select_nearby(load_latest_school_data(), int(urn))
     except Exception:
         import logging
 
         logging.getLogger(__name__).exception(
-            "Similar schools selection failed for urn=%s", urn
+            "Nearby schools selection failed for urn=%s", urn
         )
         return []
 
@@ -1000,7 +1000,7 @@ async def get_school_details(request: Request, urn: int):
         # The nearest eligible schools, closest first. Always present on a
         # build with this code; the frontend treats absent and empty
         # identically, which is what lets the two images deploy independently.
-        "similar_schools": _similar_schools_payload(urn),
+        "nearby_schools": _nearby_schools_payload(urn),
         "yearly_data": clean_for_json(school_data),
         # Supplementary data (null if not yet populated by Kestra)
         "ofsted": supplementary.get("ofsted"),