Remove Dart support and add LSP smoke coverage

[jafreck]

Summary

• remove remaining Dart extractor/CLI support and update docs/test counts
• add real-server smoke coverage for TypeScript and Pyright LSPs, including CI execution
• expand fixture snapshot coverage for additional extractor relationship/type-ref behavior

Testing

• npm test
• env LORE_RUN_LSP_SMOKE=1 npm run test:lsp-smoke

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 87.08%. Comparing base (144495f) to head (e86dd75).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #150      +/-   ##
==========================================
+ Coverage   85.54%   87.08%   +1.54%     
==========================================
  Files          76       75       -1     
  Lines        7145     7022     -123     
  Branches     2348     2297      -51     
==========================================
+ Hits         6112     6115       +3     
+ Misses       1033      907     -126     

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