DOC: update to documentation + small clean up of legacy code

[YektaY]

Description

documentation overhaul:

• dedupe the documentation
• deletes legacy content
• replace ASCII diagrams with light/dark images
• correct for drift against the code.

Motivation

The docs had accumulated significant duplication (quickstart / architecture lived in 3–4 places), orphaned references to scripts that no longer exist, and several protocol and schema-level inaccuracies that would actively mislead anyone writing a client.

Closes #34
Closes #24

Where Has This Been Documented?

The change itself is documentation

Pre-merge checklist

• Code works interactively
• Code contains descriptive docstrings
• New/changed functions and methods are covered in the test suite where possible
• Test suite passes locally
• Test suite passes on GitHub Actions