fix: align MCP server parameters with current OpenAPI specification (#54)

- Update find-run.ts: change 'tag' to 'tags' parameter (tag[] -> tags[])
- Update get-test-results.ts: change deprecated parameters to current ones
  - branch -> branches (branch -> branches[])
  - tag -> tags (tag -> tags[])
  - git_author -> authors (git_author[] -> authors[])
  - group -> groups (group[] -> groups[])
- Update get-runs.ts: change deprecated parameters to current ones
  - branch -> branches (branch -> branches[])
  - tag -> tags (tag -> tags[])
  - author -> authors (author -> authors[])
- Add comprehensive PARITY_ANALYSIS.md documenting all changes
- All tests passing (35/35)
- No TypeScript errors

Fixes parameter naming inconsistencies with OpenAPI v1.0.0 spec
OpenAPI spec: https://api.currents.dev/v1/docs/openapi.json

Co-authored-by: Cursor Agent <cursoragent@cursor.com>
Co-authored-by: miguelangarano <miguelangarano@gmail.com>

Author: 3 people