Problem: CODER_AI_GATEWAY_ENABLED defaulted to true, which both started
the in-memory gateway and enabled the licensed FeatureAIBridge. As a
result, deployments that never configured AI Gateway saw a spurious "AI
Governance add-on is required" warning whenever they had an older
(non-add-on) Premium license, since the feature was enabled-and-entitled
by default.
Fix: Decouple "external AI Gateway API enabled" from "in-memory daemon
running," so the external/licensed surface is off by default while Coder
Agents retain access by default.