chore: remove junk files and outdated archived docs

- Delete local artifacts: binaries (gosqlx, gosqlx-mcp), test binaries
  (parser.test, tokenizer.test), .out files, coverage files, .sarif
- Remove .worktrees/feature-mcp-server (PR #358 already pushed)
- git rm archive/ — explicitly labeled "should not be considered current"
  and "OUTDATED"; adds noise with no current value
- git rm docs/plans/ — LLM internal planning artifact, not user-facing doc

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: 2 people