feat: Add minutely precipitation notifications from Pirate Weather

[Orinks]

Summary

Pirate Weather provides minutely precipitation forecasts (Dark Sky-style "rain starting in 12 minutes"), but the data is currently unused. This feature should parse the minutely block, generate notifications, and include a setting to toggle them.

What the Minutely Block Contains

PW returns a minutely block with per-minute precipitation intensity and probability for the next 60 minutes. This enables notifications like:

• "Rain starting in 12 minutes"
• "Snow ending in 25 minutes"
• "Heavy rain expected in 8 minutes"
• "Precipitation clearing up in 15 minutes"

This was one of Dark Sky's most loved features.

Implementation

1. Parse Minutely Data

• Add _parse_minutely() to PirateWeatherClient
• Extract precipitation intensity, probability, and type per minute
• Detect transitions: dry→wet (precipitation starting) and wet→dry (precipitation ending)
• Calculate "starts in X minutes" / "ends in X minutes" from transition points

2. Notification Integration

• Wire into the existing notification flow (src/accessiweather/notifications/)
• Trigger notifications on precipitation transitions:
  • Precipitation starting soon (configurable threshold, e.g. within 15 min)
  • Precipitation ending soon
  • Intensity changes (light→heavy)
• Include precipitation type in notification (rain, snow, sleet, etc.)
• Respect notification cooldown to avoid spamming

3. Settings

• Add toggle: "Minutely precipitation alerts" (on/off, default on)
• Add threshold setting: "Notify when precipitation starts within X minutes" (default 15)
• Only available when Pirate Weather is the selected source (or in auto mode with PW configured)
• Settings location: Settings > Notifications or Settings > Data Sources

4. Accessibility

• Notifications should be screen reader friendly
• Use clear, spoken-style text: "Rain expected to start in about 12 minutes" not "precip_intensity transition at minute 12"
• Consider a sound event for precipitation alerts (could tie into sound packs)

References

• Pirate Weather API minutely block: https://pirateweather.net/en/latest/API/
• PW client: src/accessiweather/pirate_weather_client.py
• Notifications: src/accessiweather/notifications/
• Sound events: src/accessiweather/sound_events.py
• Pirate Weather provider: PR feat: Add Pirate Weather with full integration (#477, #481, #482, #483) #479