chore: remove leftover debug scripts and stale docs

Delete dead dev scratch (debug_python_ast*.js, test_python_inheritance.js),
the obsolete tree-sitter-dart native patch (Dart loads via WASM now and the
package is no longer a dependency), and orphaned docs superseded by the
current code and the agent-eval skill (IMPLEMENTATION_PLAN.md,
DELPHI-SUPPORT.md, run-interactive-test.md).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>