fix(weather): fix weathergov forecast day labels off by one (#4065)

While looking at all weather providers for #4063, I noticed another
unrelated bug: The weathergov forecast has been off by one day. This has
been since its first commit in 2019 and was not caused by the recent
weather refactor.

The provider built the days array correctly, but then threw away the
first entry (`slice(1)`) because it was considered "incomplete". The
problem: the template uses index position to decide what to label
"Today" and "Tomorrow" — so dropping today made Monday show up as
"Today", Tuesday as "Tomorrow", and one day disappeared entirely.

The fix is a one-liner: remove `slice(1)`. Today's entry now shows
min/max from the remaining hours of the day, which is the right
behaviour anyway. In my understanding it's not a problem at all that the
first day is incomplete.

## Before

Notice in the screenshot that it is Sunday. So after today and tomorrow,
Tuesday should come next, but it says **Wednesday** instead.

<img width="385" height="365" alt="Ekrankopio de 2026-03-22 14-37-55"
src="https://github.com/user-attachments/assets/02295cc6-4421-40a8-929e-6c6721dece97"
/>


## After

<img width="385" height="365" alt="Ekrankopio de 2026-03-22 14-38-34"
src="https://github.com/user-attachments/assets/cb51ca01-7882-4805-8cf4-a78f6721038a"
/>

Author: KristjanESPERANTO

defaultmodules/weather/providers/weathergov.js

@@ -349,7 +349,7 @@ class WeatherGovProvider {
 			days.push(weather);
 		}
 
-		return days.slice(1); // Skip first incomplete day
+		return days;
 	}
 
 	#generateWeatherObjectsFromHourly (forecasts) {

tests/unit/modules/default/weather/providers/weathergov_spec.js

@@ -241,6 +241,36 @@ describe("WeatherGovProvider", () => {
 			expect(day).toHaveProperty("weatherType");
 			expect(day).toHaveProperty("precipitationProbability");
 		});
+
+		it("should not skip the first day of forecast data", async () => {
+			const provider = new WeatherGovProvider({
+				lat: 40.71,
+				lon: -74.0,
+				type: "forecast"
+			});
+
+			const dataPromise = new Promise((resolve) => {
+				provider.setCallbacks(resolve, vi.fn());
+			});
+
+			server.use(
+				http.get(WEATHERGOV_FORECAST_URL, () => {
+					return HttpResponse.json(forecastData);
+				})
+			);
+
+			await provider.initialize();
+			provider.start();
+
+			const result = await dataPromise;
+
+			// Mock data starts on 2026-02-06 ("This Afternoon").
+			// Before the fix, slice(1) dropped today, so result[0] would have been 2026-02-07.
+			const firstDate = result[0].date;
+			expect(firstDate.getFullYear()).toBe(2026);
+			expect(firstDate.getMonth()).toBe(1); // February (0-indexed)
+			expect(firstDate.getDate()).toBe(6);
+		});
 	});
 
 	describe("Hourly Parsing", () => {