feat: implement auto-fixing pre-commit hooks

- Add stage_fixed: true to format and lint commands in lefthook.yml
- Pre-commit hooks now automatically fix formatting and linting issues
- Fixed files are automatically re-staged for commit
- Eliminates the need for manual fix-restage-retry cycles
- Typecheck and test remain as validation-only hooks

Author: steviec

lefthook.yml

@@ -2,20 +2,22 @@ pre-commit:
   parallel: true
   commands:
     format:
-      run: npm run format:check
-      fail_text: "Code formatting issues found. Run 'npm run format' to fix."
+      run: npm run format
+      stage_fixed: true
+      fail_text: 'Formatting fixes applied and staged'
 
     lint:
-      run: npm run lint
-      fail_text: "Linting errors found. Run 'npm run lint:fix' to fix auto-fixable issues."
+      run: npm run lint:fix
+      stage_fixed: true
+      fail_text: 'Linting fixes applied and staged'
 
     typecheck:
       run: npm run typecheck
-      fail_text: 'TypeScript type errors found. Fix the errors before committing.'
+      fail_text: 'TypeScript type errors found. Fix manually.'
 
     test:
       run: npm run test:unit
-      fail_text: 'Unit tests failed. Fix the tests before committing.'
+      fail_text: 'Unit tests failed. Fix manually.'
 
 pre-push:
   commands: