docs: add real screenshots to README and release notes

[arunrajiah]

Summary

Add real device screenshots to the README and GitHub Release notes so new users know what they're installing before they sideload the APK.

What's needed

The capture checklist is at docs/media/README.md. Screens to capture:

• Feed tab — mix of confidence levels (green/amber rows)
• Sighting detail — species photo, confidence pill, play button
• Species tab — species list with thumbnails
• Species detail — photo, detection count, star button
• Stats tab — bar chart + top species
• Favorites tab
• Settings tab
• Connect screen (both BirdWeather and BirdNET-Go modes)

Light and dark mode variants for each screen where practical.

Instructions

1. Run the app on a physical device or emulator with realistic data
2. Follow the naming convention in docs/media/README.md
3. Open a PR adding the images to docs/media/
4. Reference this issue in the PR description

Good first contribution — no code required, just a running station and a device.

[arunrajiah]

Status update

Screenshot spec is documented at docs/media/README.md with the naming convention, resolution requirements, and the full checklist of screens needed.

Screens still needed (all):

• Feed tab (mix of green/amber confidence rows)
• Sighting detail (photo, confidence pill, audio play button)
• Species tab (list with thumbnails)
• Species detail (photo, detection count, star button)
• Stats tab (14-day bar chart + top species)
• Favorites tab
• Settings tab — now shows the multi-station list (v0.4.0)
• Connect / Add station screen (BirdWeather and BirdNET-Go/Pi modes)

Light and dark mode variants appreciated.

Connect screen update (v0.4.0): the title now reads "Add a station" (not "Connect your station") once a station is already saved — worth capturing both states.

This is still a great first contribution — no code required, just a running station and a device. Steps in docs/media/README.md.