[FEATURE] Add a built-in video trimming/cutting tool

[maocide]

Description:

User mrtj818 on Reddit suggested adding a feature to trim longer videos down to a short loop directly within the app.

Goal:

Improve the user workflow by removing the need for a separate video editing app to prepare clips. A user could select a long video, use sliders to define a start and end point, and set that segment as their wallpaper.

Technical Considerations:

This is a complex feature that was experimented with before the initial release. The primary challenge is video re-encoding on Android.

• Simply setting start/end parameters in ExoPlayer is not sufficient for a permanent wallpaper; the file itself must be trimmed otherwise stuttering might appear, investigate more and retry.

• A more robust implementation requires a video processing/re-encoding library.

• Initial tests showed that re-encoding can sometimes corrupt video metadata, leading to the same "stretching" bug reported in Issue [BUG] Video is stretched or distorted on some devices (e.g., OnePlus) #2.

A successful implementation will require finding a stable, third-party video processing library for Android that can reliably trim videos without corrupting their metadata.

Priority:

This is a high-value, "power user" feature. It will be prioritized after critical bug fixes and more straightforward QOL improvements are complete.

Credit:

This feature was suggested by mrtj818.