Release explain-codebase 0.2.1

[danyasync]

Summary

• redesign the interactive dependency graph with a flat dark interface
• keep deterministic node positions while adding restrained node pulse and directional edge flow
• add manual placement with bounded local collision handling
• update documentation, changelog, version metadata, and regression coverage for 0.2.1

Impact

The graph stays visually active without moving its layout. Clicking no longer shifts nodes, dragged nodes keep their placement, and overlaps are resolved only among nearby nodes with strict movement limits.

Validation

• 84 tests passed, 2 skipped
• Ruff passed
• strict distribution checks passed
• desktop and mobile browser interaction checks passed
• no medium- or high-severity security findings
• clean wheel install and graph generation passed