Investigate missing weather widget in Omni/Cal brief

Findings:

• There is currently no weather widget rendering path in Omni/Cal/Web.hs brief view.
• Omni/Cal/Weather.hs exists and can fetch/cached NWS weather, but getWeather/newWeatherCache are never called anywhere.
• Git history shows Weather.hs was introduced in commit 3f6bc922 (Dashboard improvements: weather, sunrise/sunset...), but the Web.hs diff in that commit only integrated sunrise/sunset guide lines via Weather.sunTimes and did not add brief weather UI.
• Searched all history for Weather.getWeather usage in Web and found none.

Conclusion:

• The weather widget appears to have never been wired in committed code; likely intended but incomplete in that commit.

Implemented weather wiring for Omni/Cal brief view.

What changed:

• Wired weather cache lifecycle into cal app startup:
• main now initializes Weather.newWeatherCache
• mkApp now initializes Weather.newWeatherCache
• app signature now carries Weather.WeatherCache and routes []/brief pass it through
• briefPage now fetches weather via Weather.getWeather (today-only) and renders a weather section card.
• Added brief weather UI rendering helpers:
• briefWeather
• renderWeatherPeriod
• Added CSS styles for weather card/period chips in calStyles.

Verification:

• typecheck.sh Omni/Cal/Web.hs
• lint Omni/Cal/Web.hs
• bild Omni/Cal/Web.hs
• bild Omni/Web/Core.hs
• runtime smoke test: started cal-web in tmux, requested /brief, verified Weather section and weather content present in rendered HTML.

Commit:

• b0f5316f

Follow-up implemented for /brief weather day selection.

Request addressed:

• When navigating to a future day (e.g. tomorrow), /brief now shows that day's forecast.
• If no forecast exists for the selected day, the weather widget is omitted.

Code changes:

• Omni/Cal/Weather.hs
• Extended ForecastPeriod with fpStartTime (from NWS period startTime).
• Increased parsed forecast horizon to 14 periods.
• Omni/Cal/Web.hs
• Always fetch weather once for /brief, then select display model by selected day.
• Added day-specific weather card builder:
• today => current conditions card
• future day => forecast card built from periods whose startTime date matches selected day
• past day or no matching periods => no weather card rendered

Validation:

• typecheck.sh Omni/Cal/Web.hs
• lint Omni/Cal/Web.hs Omni/Cal/Weather.hs
• bild Omni/Cal/Web.hs
• bild Omni/Web/Core.hs
• smoke test (tmux + curl):
• /brief?from=tomorrow => weather widget present
• /brief?from=+30days => weather widget absent

Commit:

• 37bc5a22