[Feat] Background Changes Based on Time of Day

**Is your feature request related to a problem? Please describe.**
I'm always frustrated when the app's background remains static and doesn't reflect the time of day. This makes the interface feel less dynamic and engaging. A more adaptive background could enhance user experience and make the app feel more in tune with the user's environment.

**Describe the solution you'd like**
I would like the app's background to change dynamically based on the time of day. For example:
- Morning: Bright, warm colors like soft yellow or light orange to mimic
- Afternoon: Clear, neutral colors like light blue or white to represent
- Evening: Warm, soothing tones like amber or light purple to reflect
- Night: Dark, calming shades like deep blue or black with stars to mimic the night sky.

Start by locating the Flutter app entry point and the widget or theme responsible for rendering the background. Determine how the app obtains the current time and where background styling is defined. Done means the background visibly changes for morning, afternoon, evening, and night according to the requested color examples.

Written by the indexing model from the issue text.