[Request] Fail fast when the specified symbol is not available on the account #15

Summary

When a cBot is started with a symbol that is not available on the account, it can remain in the "started" state without a clear error, and on_start is never called.

Expected behavior

If the specified symbol is not available, the system should fail fast, or at least emit a clear error and stop.

Actual behavior

• No explicit error is shown
• The container stays in the started state
• on_start is never called

Environment

• Execution method: Docker
• Image: ghcr.io/spotware/ctrader-console:5.7.10
• Condition: symbol not available on the account