fix: recalculate item width when number of forecast changes

[troinine]

This PR fixes an issue where forecast data was not rendered on delayed forecast data. If the forecast is initially empty and is received later, the card didn't render forecast data at all.

[Copilot]

Pull request overview

This PR addresses an issue where forecast data was not rendered when it arrived delayed (initially empty but received later). The fix adds logic to detect when the number of forecast items changes and triggers a layout recalculation to properly display the forecast data.

• Tracks previous forecast lengths before updating forecast data
• Recalculates layout when the number of forecast items changes
• Adds test coverage for the layout recalculation behavior

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 4 comments.

File	Description
src/weather-forecast-card.ts	Adds logic to detect forecast length changes and trigger layout recalculation
test/weather-forecast-card.test.ts	Adds test to verify layout recalculation when forecast item count changes
test/mocks/hass.ts	Updates mock updateForecasts method to accept forecast type parameter and trigger subscriptions

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[Copilot]

Pull request overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated 4 comments.

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[Copilot]

Pull request overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated no new comments.

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