fix: drop premature TypeScript 6 range

[WillieRuemmele]

Summary

• Removes the || ^6 from the typescript dependency range, reverting to ^5.5.4
• TS 6 is not yet stable; the premature range causes write-dependencies.js to propagate ^5.5.4 || ^6 to all consumer repos on every install, which could break builds if TS 6 introduces breaking changes

Test plan

• Verify sf-install no longer writes || ^6 into consumer package.json files