Add post bounty first step component coverage

[CodecCods]

Fixes stakwork/sphinx-tribes#902

Summary

• add WorkspaceHeader coverage for signed-in bounty managers opening the post bounty modal
• assert the first bounty-type selection step shows Freelance Job Request, Live Help, and Coming soon
• verify Start advances to Basic info and close dismisses the modal

Validation

• REACT_APP_IS_TEST=true NODE_ENV=test node node_modules/jest/bin/jest.js --runTestsByPath src/pages/tickets/tests/WorkspaceHeader.spec.tsx --runInBand --no-cache --coverage=false