conductor workflow create gives no success feedback, then 500 error on retry

[nthmost-orkes]

Problem

conductor workflow create <file> prints nothing on success — no confirmation that the workflow was registered. A new user following the quickstart has no signal that the command worked.

If they run it a second time (because they weren't sure it worked), they get:

Error: Failed to create workflow: Workflow with hello_workflow.1 already exists! (status: 500)

A 500 status code for "already exists" is surprising. A new user's first instinct is that something is broken.

Steps to reproduce

conductor workflow create workflow.json
# (no output other than "Auto-detected Conductor server at http://localhost:8080")
conductor workflow create workflow.json
# Error: Failed to create workflow: Workflow with hello_workflow.1 already exists! (status: 500)

Fix

1. conductor-cli: Print a success message on workflow create — e.g., Workflow 'hello_workflow' (version 1) registered successfully.
2. conductor-cli: If the server returns "already exists," treat it as a non-error (or at minimum return a 409-style message, not a 500 error message)
3. Server: Consider returning 409 Conflict instead of 500 for duplicate workflow definitions

Affects

• conductor-oss/conductor-cli (primary fix — success output + error handling)
• conductor-oss/conductor (server-side status code is a secondary issue)

[nthmost-orkes]

Fixed in conductor-oss/conductor-cli#78 (merged). conductor workflow create now prints Workflow '<name>' version <N> registered successfully on success.