feat: implement timeout handling for environment and package manager registration

[eleanorjboyd]

waitForEnvManager created a deferred that had no timeout, no cancellation, and no fallback- this add the timeout. This meant that if any project's configured default manager never registered (e.g., settings point to an uninstalled extension or a manager whose binary isn't found), the deferred promise would hang forever. ie one bad project poisoned global calls

now:

• A single misconfigured project can no longer hang the entire extension indefinitely
• Consumers still get results from all managers that registered normally
• The timeout 30s accommodate slow 3rd-party extension activation
• The warning log provides diagnostics for investigating missing managers