Add Rust Generator Add-on for procedural rust material

[SaikiranShet-9800]

Summary
This pull request introduces a Procedural Rust Generator add-on for Blender. The tool
creates a customizable rust material using procedural node networks, allowing users to
quickly generate realistic metal aging, corrosion, and surface wear without external
textures. The add-on is designed to be lightweight, easy to integrate, and suitable for
both real-time and high-quality rendering workflows.

Key Features

• Generates a fully procedural rust material using Blender’s node system.
• Adjustable parameters for rust intensity, color variation, roughness, metalness,
  surface spread, and edge wear.
• Works on any object with a UV map or procedural coordinates.
• Non-destructive workflow that does not rely on image textures.
• Simple API structure for developers who wish to extend the generator.
• Compatible with Blender’s Principled BSDF and Cycles/Eevee render engines.

Technical Overview
The generator constructs a node tree consisting of:

• Noise functions to simulate corrosion patterns.
• Color ramps for controlling oxidation levels.
• Masking logic to drive rust accumulation on edges and cavities.
• Mix shaders to blend rust with underlying metal.
• Optional displacement or bump mapping for surface detail.

The add-on is implemented as a Python operator that automatically builds and assigns
the material to the selected object. The code is modular, making it easy to update or
customize individual components of the shader network.

Motivation
Procedural rust materials are widely used in hard-surface modeling, game asset creation,
and environmental texturing. Existing workflows often rely on external texture maps,
which limits flexibility and increases file size. This add-on provides a fully procedural
solution that allows artists to generate rust effects directly inside Blender with full
control over the appearance.

Documentation

• The code includes comments explaining each part of the node-generation process.
• A usage section has been added describing how to run the operator.
• Parameters and their effects are documented for clarity.

Request
Please review this addition and consider merging it into the project. Feedback and
suggestions for improving the material, node structure, or user interface are welcome.