v1.0.2

feat: custom background image with opacity and dim controls(#21)

Settings > Background lets the user pick an image (stored in the app's private documents directory), fade it with an opacity slider, dim it for text readability, or reset to the built-in colors. The image renders app-wide behind transparent scaffolds; bars on the server screen turn translucent so the picture shows through there too.

Feature by @xiaoprincess (#21). Merged with master-priority conflict resolution: background settings re-modeled onto the current Notifier idiom (lib/models/background_settings.dart) since app_settings.dart no longer exists, and the scaffold/bar tweaks re-applied onto the rewritten screens. Newer full-screen pages also transparent.

Co-authored-by: xiaoprincess <xyc02585@gmail.com>