fix(osm): gate place search like /api/overpass after #1308

#1308 moved /api/overpass to the keyless cross-site gate: foreign origins
and cross-site fetches are still refused, but forwarding headers are not,
so the map works behind a reverse proxy. Voice place search spends the same
operator Overpass, so it now uses the same gate; with the stricter one,
place search failed behind a proxy while the map kept working. The prompt
lint note records the merged size, 55,370 with an operator Overpass.

server/providers/overpass/osmFeaturesRoute.js

@@ -1,6 +1,6 @@
 import path from 'node:path';
 import { makeRateLimiter, clientKey } from '../common/rate-limit.js';
-import { admitSameSite } from '../common/same-site.js';
+import { admitSameSiteKeyless } from '../common/same-site.js';
 import { createBoundedCache } from '../common/boundedCache.js';
 import {
   compileOsmFeatureQuery,
@@ -201,8 +201,9 @@ export function installOsmFeaturesRoute(
   middlewares.use('/api/osm/features', async (req, res) => {
     const send = sender(res);
     if (req.method !== 'GET') return send(jsonError(405, 'Method Not Allowed'));
-    // Quota-bearing: a page elsewhere must not spend the operator's Overpass.
-    if (admitSameSite(req, res)) return undefined;
+    // A page elsewhere must not spend the operator's Overpass. The keyless
+    // gate, as on /api/overpass: voice works behind a reverse proxy too.
+    if (admitSameSiteKeyless(req, res)) return undefined;
     if (!configured())
       return send(
         jsonError(503, 'Place search needs a configured Overpass server.', {

src/tooling/osmFeaturesRoute.test.mjs

@@ -380,6 +380,14 @@ test('a cross-site page cannot spend the operator Overpass', async () => {
     'sec-fetch-site': 'same-origin',
   });
   assert.equal(own.status, 200);
+  // Like /api/overpass, it works behind a reverse proxy: forwarding headers
+  // alone are not a refusal.
+  const proxied = await request('preset=school&bbox=0,0,2,2', undefined, {
+    host: 'localhost:5173',
+    'sec-fetch-site': 'same-origin',
+    'x-forwarded-for': '203.0.113.7',
+  });
+  assert.equal(proxied.status, 200);
 });
 
 test('an upstream refusal is not an empty answer', async () => {

src/voice/pointAndAsk.test.mjs

@@ -346,7 +346,8 @@ test('deixis prompt lint: one short rule, and every sentinel it names exists in
   // it to 51,646. Voice geometry (resolve_area, find_imagery, osm_query and
   // the analyst area scopes) raised the ceiling to 55,500; tightening the
   // AREAS rule and the area tool descriptions left it at 55,263 with an
-  // operator Overpass, a deliberate ~240-character margin. A new tool or rule
+  // operator Overpass; main's Sea Marks and Ski Pistes layers bring it to
+  // 55,370, ~130 under. A new tool or rule
   // has to fit under this ceiling.
   const size = instructions.length + JSON.stringify(GEV_REALTIME_TOOLS).length;
   assert.ok(size <= 55_500, `prompt size ${size}`);