chore: cleanup docs md config files

[dgtalbug]

This pull request primarily reorganizes and renames feature specification files to reflect updated feature IDs and branches, and updates documentation to match these changes. It also removes outdated planning and PR summary files for the previous test infrastructure feature. The main themes are feature renaming and documentation cleanup.

Feature renaming and documentation updates:

• Renamed all files and updated internal references for the test infrastructure feature from 014-test-infrastructure to 003-test-infrastructure, including branch names and feature IDs in plan.md, spec.md, tasks.md, and research.md [1] [2] [3] [4] [5] [6].
• Renamed and updated all references for the interactive UI enhancements feature from 018-interactive-ui-enhancements to 004-interactive-ui-enhancements, including file names, feature IDs, and branch names in all related documents [1] [2] [3] [4] [5] [6] [7].

Documentation cleanup:

• Removed the old planning summary and PR description files for 014-test-infrastructure, as these are now obsolete after the renaming and migration to the new feature ID [1] [2].

Minor tooling update:

• Removed the golangci-lint config verify line from new.sh, possibly as part of cleaning up unused tooling scripts.