keep tile outlines honest when the anchor tile fails to load

A building or grounds outline from tiles now needs the tile holding the
anchor: when that tile fails and only neighbours load, no neighbouring
building or area stands in. Nominatim name tags holding several
";"-separated names match each name. Document recovery from a stuck
public-Nominatim dispatch marker, correct the phone credit comment,
drive the slow-device queue test with a mocked performance clock, and
credit GitHub handles in the changelog.

.env.example

@@ -280,6 +280,11 @@ OVERPASS_UPSTREAMS=
 # Public-instance requests per UTC day, outlines and search together. Not
 # applied to your own NOMINATIM_URL.
 # NOMINATIM_DAILY_CAP=50
+# Public-instance pacing is shared through .gev-cache/nominatim/state.json. If
+# the server stopped mid-request (or its disk filled), it leaves a
+# state.json.dispatch.* marker and refuses public lookups ("unfinished durable
+# Nominatim dispatch") rather than risk breaking the spacing. With the server
+# stopped, delete those marker files to resume.
 # PHOTON_URL: keyless place search endpoint used by the browser
 # (e.g. https://photon.example.org/api/). Unset uses photon.komoot.io; set it
 # empty to disable.