fix(create-plugin): use correct @cybozu/eslint-config flat config API

[nameless-mc]

Why

The ESLint configuration in create-plugin templates was not using the @cybozu/eslint-config flat config API correctly, causing npm run lint to fail in generated plugin projects.

Specific issues:

• minimum template: Attempted to spread kintone(), prettier(), etc. directly without calling them as functions
• modern template: Used presets/prettier which does not include kintone globals, resulting in kintone is not defined errors

What

• minimum template: Fixed to call kintone() and prettier() as functions
• modern template: Changed from presets/prettier to presets/kintone-customize-prettier (includes kintone globals)
• test:ci: Fixed pnpm test test:generator to pnpm test && pnpm test:generator to ensure generator tests run correctly

How to test

pnpm --filter @kintone/create-plugin test:generator

Checklist

• Read CONTRIBUTING.md
• Updated documentation if it is required.
• Added tests if it is required.
• Passed pnpm lint and pnpm test on the root directory.