Fix API group mismatch in operator webhook manifest for MCPExternalAuthConfig

[ChrisJBurns]

Summary

The MCPExternalAuthConfig webhook entry in cmd/thv-operator/config/webhook/manifests.yaml uses the wrong API group toolhive.stacklok.com instead of the correct toolhive.stacklok.dev. The webhook path also uses toolhive-stacklok-com instead of toolhive-stacklok-dev.

The other two webhooks in the same file and the top-level config/webhook/manifests.yaml all correctly use toolhive.stacklok.dev.

Impact

• Latent bug that would surface if webhooks were ever enabled
• Would target a non-existent API group, causing the webhook to silently not fire

Location

• cmd/thv-operator/config/webhook/manifests.yaml lines 13 and 18

Fix

Change toolhive.stacklok.com to toolhive.stacklok.dev in the apiGroups rule, and update the path from toolhive-stacklok-com to toolhive-stacklok-dev.