chore: fix pre-commit hook to enforce formatting and linting (#2297)

The pre-commit hook existed but was not executable and used raw
prettier instead of lint-staged. This fixes:

- Make .husky/pre-commit executable (was -rw-r--r--)
- Use `npx lint-staged` instead of raw prettier/eslint commands
- Remove deprecated husky v4 config from package.json (hooks key)
- Remove unnecessary `git add` from lint-staged (auto-staged in v15)
- Add eslint --fix to lint-staged for JS/TS files

All contributors now get automatic formatting + linting on commit.

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.husky/pre-commit

@@ -1,6 +1 @@
-# .husky/pre-commit
-prettier $(git diff --cached --name-only --diff-filter=ACMR | sed 's| |\\ |g') --write --ignore-unknown
-git update-index --again
-
-# Add linting
-npm run lint
+npx lint-staged

package.json

@@ -22,15 +22,12 @@
   },
   "keywords": [],
   "author": "Logan Yang",
-  "husky": {
-    "hooks": {
-      "pre-commit": "lint-staged"
-    }
-  },
   "lint-staged": {
     "*.{js,jsx,ts,tsx,json,css,md}": [
-      "prettier --write",
-      "git add"
+      "prettier --write"
+    ],
+    "*.{js,jsx,ts,tsx}": [
+      "eslint --fix --no-warn-ignored"
     ]
   },
   "license": "AGPL-3.0",