feat: add litellm to new aitooling ArgoCD project (#94)

Deploys LiteLLM proxy with CNPG PostgreSQL (3-instance HA), PgBouncer
pooler, and Redis cache. Introduces a dedicated aitooling AppProject and
ApplicationSet to keep AI tooling services separate from platform infra.

Reviewed-on: #94

apps/base/litellm/redis-pvc.yaml

@@ -0,0 +1,14 @@
+---
+apiVersion: v1
+kind: PersistentVolumeClaim
+metadata:
+  name: litellm-redis-data
+  namespace: litellm
+spec:
+  accessModes:
+    - ReadWriteOnce
+  resources:
+    requests:
+      storage: 5Gi
+  storageClassName: cephrbd-fast-delete
+  volumeMode: Filesystem