right-size memory requests to unblock GPU workloads and fix dbaas quota [ci skip]

- nvidia: custom LimitRange (128Mi default, was 1Gi from Kyverno) to stop
  inflating GPU operator init containers; saves ~2.5Gi on GPU node
- nvidia: dcgm-exporter 1536Mi → 768Mi (actual usage 489Mi)
- monitoring: prometheus server 4Gi → 3Gi (actual usage 2.6Gi)
- onlyoffice: 2304Mi → 1536Mi (actual usage 1.3Gi)
- immich: frame explicit 64Mi resources (was getting 1Gi LimitRange default)
- dbaas: quota limits.memory 20Gi → 24Gi to fit 3rd MySQL replica

Root cause: Kyverno tier-2-gpu LimitRange injected 1Gi on every NVIDIA init
container (no explicit resources), wasting ~2.5Gi scheduling overhead on the
GPU node. Combined with over-requesting, frigate and immich-ml couldn't schedule.

stacks/nvidia/modules/nvidia/values.yaml

@@ -18,13 +18,13 @@ driver:
     config:
       name: time-slicing-config
 
-# DCGM Exporter - reduced from 2560Mi to 1536Mi based on VPA upper bound of 1459Mi (1.05x margin)
+# DCGM Exporter - reduced to 768Mi (actual usage ~489Mi, 1.5x margin)
 dcgmExporter:
   resources:
     requests:
-      memory: "1536Mi"
+      memory: "768Mi"
     limits:
-      memory: "1536Mi"
+      memory: "768Mi"
 
 # CUDA Validator - reduced from 1024Mi to 256Mi (one-shot job)
 validator: