[fix] workflows not camelised on push, breaking invariant

[PennyroyalTea]

Fixes a bug reported in #45

Summary

• Fix 422 UnprocessableEntityError when pushing agents with
  workflows (Elevenlabs agents push fails with 422 UnprocessableEntityError (workflow edges without conditions) ElevenLabs CLI v0.3.3 #45)
• Workflow edge conditions
  (forward_condition/backward_condition) were not being
  converted to camelCase before sending to the API, causing
  the API to reject them as missing

Changes

• Apply toCamelCaseKeys() to workflow in createAgentApi and
  updateAgentApi
• Add tests for workflow edge condition case conversion
• Update existing workflow tests to expect camelCase output

Test plan

• New tests fail without fix, pass with fix
• All 158 tests pass