Implement process killing animation and tracking

[Harshjeet]

Added functionality to track killed process IDs and animate their removal from the process list.

[Purian23]

Hi there, thanks for the PR! The inline kill button is a really neat UX addition!

A few items:

1. Let's Avoid Custom Timers/Canvas: We keep the shell primarily event-driven. Let's replace the particle canvas with a standard declarative QML transition instead (e.g., fading the row's opacity and collapsing its height to 0).
2. Fix Infinite Binding Loop: Currently, updating killedPids inside onFilteredProcessesChanged triggers a synchronous recursion loop that freezes the shell.

Once those adjustments are made, we should be good to go.

[Purian23]

Closing in favor of updated PR #2588