Accept "socket" as a DSN query parameter

[rolandwalker]

Description

socket as a query parameter instead of --socket as a CLI flag allows it to be saved in a DSN alias.

Checklist

• I added this contribution to the changelog.md file.
• I added my name to the AUTHORS file (or it's already there).
• To lint and format the code, I ran

  uv run ruff check && uv run ruff format && uv run mypy --install-types .

[github-actions]

Findings
No correctness or security issues found in the change itself.

Test Gaps / Edge Cases

1. CLI precedence: add a test that --socket overrides ?socket=... in the DSN to lock in the intended precedence behavior. This matters because socket = socket or params[0] relies on truthiness and could regress if defaults change. (mycli/main.py:1993, test/test_main.py:929)
2. URL-encoded socket paths: add a test for a percent-encoded socket path (e.g., %2Ftmp%2Fmysql.sock) to ensure parsing stays correct across refactors that might change query parsing. (test/test_main.py:929)

If you want, I can add the tests.