refactor(lib-internal): replace require() with ES module imports

[jdalton]

Summary

Convert lazy require() calls to static ES module imports in lib-internal package for better bundling and tree-shaking.

Changes

package-extensions.ts

// Before
const yarnPkgExtensions = require('@yarnpkg/extensions')

// After
import yarnPkgExtensions from '@yarnpkg/extensions'

prompts.ts

// Before
const confirmExport = /*@__PURE__*/ require('@inquirer/confirm')
const confirmRaw = confirmExport.default ?? confirmExport
// ... similar for input, password, search, select

// After
import confirm from '@inquirer/confirm'
import input from '@inquirer/input'
// ... etc
const confirmRaw = confirm

Benefits

✅ Better bundling - static imports enable tree-shaking
✅ Cleaner code - no more default ?? fallback patterns
✅ Consistent style - aligns with ES module best practices
✅ Improved performance - eliminates runtime require() resolution

Test Plan

• Type check passes
• Security checks pass
• Verify prompt functionality in interactive commands
• Verify package extensions work correctly

Impact

Low risk - Simple import conversion with no logic changes. The same modules are loaded, just with static imports instead of dynamic require().