feat: ignore all node_modules and .git dirs by default

[jedwards1211]

PR Checklist

• Addresses an existing open issue: fixes 🚀 Feature: Change default value for --watch-ignore to **/node_modules, **/.git #5203
• That issue was marked as status: accepting prs
• Steps in CONTRIBUTING.md were taken

Overview

Just adds **/ before the default ignore patterns so that all node_modules and .git dirs get ignored, not just ones in the root folder.

[JoshuaKGoldberg]

Putting in draft per #5203 (comment). Sorry for being misleading!

[Copilot]

Pull Request Overview

This PR updates the default watch-ignore patterns to recursively ignore all node_modules and .git directories, not just those at the root.

• Updated "watch-ignore" in lib/mocharc.json to use "/node_modules" and "/.git".
• Ensures that file watchers effectively skip these directories regardless of their location.

Comments suppressed due to low confidence (1)

lib/mocharc.json:9

• Consider verifying that the recursive '**/' pattern does not ignore directories that should remain watched (e.g., for debugging or testing purposes). If necessary, update the documentation to clearly communicate the change in behavior.

"watch-ignore": ["**/node_modules", "**/.git"]