Korum: Document the compiler architecture in an ARCH.md file

[korum-app]

Korum Task

• Task ID: k971ej7jth31xtzwm72w58jsn582f6wd
• Revision: 2

Description

Document the compiler architecture in an ARCH.md file

Summary

I have created the ARCH.md file in the repository root. It provides a high-level overview of the compiler architecture and includes a detailed section on graph visualization.

The graph visualization section now includes:

1. Explanation of the --graph and --enable-dom-labels CLI flags.
2. A programmatic guide on using the Graph struct, including:
   • Initializing the Graph with Graph::new().
   • Loading the program with load_program().
   • Generating the DOT string using the build() method.
   • A complete code example showing how to write the output to a file.
3. Instructions on how to render the resulting DOT file using Graphviz.