Updated Feedback shadow for Logic Gates

[Amadeus1791]

This PR updates the shadow figures to be aligned with the new modernized design of the gates done in #676
It also replaces the XOR mode drawing in the gate feedback figures with a more consistent custom fill approach.

Problem with XOR Mode

The previous feedback figures used XOR mode for rendering, which has several drawbacks:

• Creates white artifacts when shapes overlap with each other
• Inconsistent appearance depending on background colors
• Poor visibility against certain backgrounds

Solution

I've replaced XOR mode with a custom fill approach in these feedback figures:

The changes done were:

1. Remove XOR mode completely
2. Use dedicated feedback colors (defined in LogicColorConstants)
3. Maintain the exact shape dimensions and proportions of original figures

new shadow figures for the gates: