Source Valmiera's Faktiskā temperature from Priekuļi as a temporary substitute

LVĢMC's open-data station list has no station in or near Valmiera at all
(confirmed live 2026-08-23 in OpenDataStationService.scala), so that fixed
position has been silently blank. Priekuļi is the closest currently-
reporting station -- measured against the app's own calibrated map
coordinates (~56px away vs. the next-closest candidate, Rūjiena, at ~81px),
not a guess. Same pattern already used for Stende/Talsi and Zīlāni/Jēkabpils.

Implemented client-side in Faktiskā's fetch only: query Priekuļi's reading,
remap it back onto the "Valmiera" key before it reaches the rest of the
component. Valmiera's marker position and on-map label are untouched (both
are tied to Valmiera's real map location, not Priekuļi's) -- only the data
source for that one slot changes. This also fixes a second, previously
unexplained symptom for free: the weather-symbol picker only lists cities
with a value, so Valmiera never appeared there either; it now does.

Provisional pending direct confirmation from LVĢMC -- documented as such in
PRODUCT_WORKFLOWS.md, matching how Stende/Zīlāni are already flagged.

Verified: typecheck clean, production build succeeds, headless-browser
checks confirm Valmiera's field shows Priekuļi's real live value (14.8°C,
fresh timestamp, not flagged manual/stale) and now appears in the
weather-symbol exceptions list (13 cities, was 12).

web/src/pages/map-graphics/MapGraphics.tsx

@@ -7,10 +7,26 @@ import type { FaktiskaTemplate } from "./faktiskaTemplates";
 import "./mapGraphics.css";
 
 type LatestTemperature = { city: FaktiskaStation; observedAt: string; value: number | null };
+type RawLatestTemperature = { city: string; observedAt: string; value: number | null };
 
 const emptyValues = (): Record<FaktiskaStation, string> =>
     Object.fromEntries(faktiskaStations.map(city => [city, ""])) as Record<FaktiskaStation, string>;
 
+// LVĢMC's open-data station list has no station in or near Valmiera at all
+// (confirmed live 2026-08-23, see OpenDataStationService.scala). Priekuļi is
+// the closest currently-reporting station (verified against the app's own
+// calibrated map coordinates: ~56px away vs. the next-closest candidate's
+// ~81px). Valmiera's marker position and on-map label stay exactly where
+// they are -- only the queried data source for that one slot changes.
+// Temporary, same pattern as Stende/Zīlāni substituting for Talsi/Jēkabpils
+// (see PRODUCT_WORKFLOWS.md); pending confirmation directly from LVĢMC.
+const stationSubstitutes: Partial<Record<FaktiskaStation, string>> = {
+    "Valmiera": "Priekuļi",
+};
+const substituteToStation = new Map(
+    Object.entries(stationSubstitutes).map(([station, substitute]) => [substitute, station as FaktiskaStation])
+);
+
 export function Faktiska() {
     const [values, setValues] = createSignal(emptyValues());
     const [overrides, setOverrides] = createSignal<Set<FaktiskaStation>>(new Set());
@@ -21,9 +37,14 @@ export function Faktiska() {
         : { width: 3840, height: 1440 };
 
     const fetchLatest = async (): Promise<LatestTemperature[]> => {
-        const response = await fetch(`${apiHost}/api/query/latest-temperatures/${faktiskaStations.join(",")}`);
+        const queryCities = faktiskaStations.map(city => stationSubstitutes[city] ?? city);
+        const response = await fetch(`${apiHost}/api/query/latest-temperatures/${queryCities.join(",")}`);
         if (!response.ok) throw new Error(`Latest observations failed (${response.status})`);
-        return response.json();
+        const observations: RawLatestTemperature[] = await response.json();
+        return observations.map(observation => ({
+            ...observation,
+            city: substituteToStation.get(observation.city) ?? observation.city as FaktiskaStation,
+        }));
     };
     const [latest, { refetch }] = createResource(fetchLatest);