feat(infra): add GitLab Agent for Kubernetes config

Registers foxhunt-production agent with CI and user access
for in-cluster kubectl from GitLab pipelines.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.gitlab/agents/foxhunt-production/config.yaml

@@ -0,0 +1,12 @@
+# GitLab Agent for Kubernetes configuration
+# https://docs.gitlab.com/ee/user/clusters/agent/install/
+
+ci_access:
+  projects:
+    - id: root/foxhunt
+
+user_access:
+  projects:
+    - id: root/foxhunt
+      access_as:
+        agent: {}