Add Snap Packaging for eSim

[Aishw31]

Purpose

This pull request introduces Snap packaging support for eSim to simplify installation and make it easier to distribute across various Linux distributions.

Approach

This PR adds snap packaging by:

• Creating snap/snapcraft.yaml configuration.
• Bundling all required dependencies to ensure proper snap confinement.
• Adding desktop integration (application icon and .desktop launcher).
• Verifying that GUI, schematic editor, and netlist generation work in the snap environment.

Feature Status

• GUI: Working
• Schematic Editor: Working
• KiCad to NGSpice Converter: Working
• NGSpice Simulation: Not working properly
• NGHDL: Working

Known Issues

• NGSpice simulation is failing.
  Possible causes:
  • Restricted file access due to snap confinement.
  • Missing environment variables or incorrect paths.
  • Required snap interfaces not connected or declared.

Testing Instructions

1. Build the snap:
   snapcraft

2. Install locally:
   sudo snap install esim_*.snap --dangerous

3. Run eSim:
   esim

Next Steps

• Investigate and resolve NGSpice simulation issues.
• Consider integrating snap build into CI/CD pipelines.
• Improve documentation for snap usage and troubleshooting.