CLI returns exit code 0 even on errors — breaks scripting

[TheTrustedAdvisor]

Problem

The main() function (line 3002-3005) always exits with code 0, regardless of whether the command succeeded or failed:

def main():
    parser = build_parser()
    args = parser.parse_args()
    args.func(args)  # No return value checked, no sys.exit()

All cmd_* functions print error messages but return None. This means:

tmx login --email wrong@example.com && echo "Login successful!"
# Prints "❌ Login fehlgeschlagen" AND "Login successful!" — exit code is always 0

This breaks shell scripting, CI/CD pipelines, and AI-agent tool use where the exit code determines success/failure.

Proposed Fix

Have cmd_* functions return a boolean or use sys.exit(1) on errors:

def main():
    parser = build_parser()
    args = parser.parse_args()
    result = args.func(args)
    if result is False:
        sys.exit(1)

Then update each cmd_* function to return False on error paths (where they currently just print("❌ ...") and return).

Impact

• Severity: MEDIUM (affects scripting and programmatic use)
• Effort: Low (add return False to error paths in each cmd function)