fix(weather): use nearest openmeteo hourly data (#4123)

Open-Meteo updates `current_weather` every 15 minutes, but the hourly
array only has entries at full hours. The old code did an exact
timestamp match - so at 14:15, 14:30 or 14:45 it never found a match and
silently fell back to index 0, showing midnight values for humidity,
feels-like temp, precipitation, etc.

Fix: `findLastIndex((hour) => hour.time <= currentMs)` - the last hourly
entry at or before the current time.

While fixing the bug I found several dead branches left over from the
#4032 refactor: a path for pre-transposed hourly data that
`#parseWeatherApiResponse` makes unreachable, an `Array.isArray` guard
that's always true, and a `Log.debug` inside the dead branch. Removing
those accounts for most of the ~40 deleted lines - the actual fix is one
line.

Fixes #4122.

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

@@ -144,12 +144,15 @@ describe("OpenMeteoProvider", () => {
 			provider.start();
 
 			const result = await dataPromise;
+			const currentHourUnix = Math.floor(currentData.current_weather.time / 3600) * 3600;
+			const currentHourIndex = currentData.hourly.time.findIndex((time) => time === currentHourUnix);
 
 			expect(result).toBeDefined();
 			expect(result.temperature).toBe(8.5);
 			expect(result.windSpeed).toBeCloseTo(4.7, 1);
 			expect(result.windFromDirection).toBe(9);
-			expect(result.humidity).toBe(83);
+			expect(result.humidity).toBe(currentData.hourly.relativehumidity_2m[currentHourIndex]);
+			expect(result.humidity).not.toBe(currentData.hourly.relativehumidity_2m[0]);
 		});
 
 		it("should include sunrise and sunset from daily data", async () => {