Update GUI design documentation and wireframes

[sarayureddyyy]

Summary

Adds GUI design documentation for the FIXS configuration editor, including wireframes and descriptions of the proposed user interface and workflow.

The design focuses on simplifying the user experience by guiding users through a step-by-step configuration process instead of exposing all settings at once. It includes:

• Traffic simulator selection
• Integration layer configuration (Application, XIL, CARLA, IPG CarMaker)
• Simulation setup and vehicle field customization
• Final script generation

Each section is documented with corresponding wireframes and mapped to relevant config.yaml fields.

Related Issues / Tasks

Related to #121. This PR provides design and wireframes; implementation will be handled in a future issue.

Type of Change

• Bug fix
• New feature
• Maintenance / Refactor
• [✓ ] Documentation
• Test case / scenario update

Affected Modules / Components

docs/gui-design/wireframes

Test Cases

Environment

Only fill in the tools used for testing this PR:

• Python version:
• MATLAB/Simulink/dSPACE version:
• SUMO version:
• VISSIM version:
• IPG CarMaker version:

Checklist

• [ ✓] Code compiles/runs as expected
• [ ✓] Tests pass locally
• [ ✓] Documentation is updated (if applicable)
• [ ✓] Relevant issues are linked
• [ ✓] Version-specific changes are noted (if any)

Additional Notes (optional)

Use this figma link to get a more detailed description of user flow and final documentation: https://www.figma.com/make/I8fRVgxa7i6hYewoFJE4nC/Interactive-Flowchart-Home-Page?t=gvtrS9K86mVcu9FY-1