chore: upgrade husky from 4.x to 9.x

[hb2708]

Summary

Upgrade husky from 4.2.5 to 9.x. This is a complete configuration format change — v4 uses package.json hooks, while v9 uses a .husky/ directory with shell scripts.

Current → Target

Package	Current	Latest
husky	4.2.5	9.1.7

Why Upgrade

• v4 is unmaintained and uses a deprecated installation approach
• v9 is faster, simpler, and uses native Git hooks
• Smaller install footprint

Migration Steps

1. Remove old husky config from package.json:

   // DELETE this block from package.json:
   "husky": {
     "hooks": {
       "pre-commit": "yarn ci"
     }
   }

2. Install and initialize:

   yarn add --dev husky@latest
   npx husky init

3. Create the pre-commit hook:

   echo 'yarn ci' > .husky/pre-commit

4. Add prepare script to package.json:

   "scripts": {
     "prepare": "husky"
   }

5. Test — make a commit and verify the pre-commit hook runs yarn ci
6. Add .husky/ directory to git

Files Affected

• package.json — remove husky.hooks, add prepare script, upgrade dependency
• .husky/pre-commit — new file with hook script

References

• Husky Migration Guide
• Husky Docs