Add secrets to MCP umbrella values for deployment

Individual MCP charts don't support existingSecret pattern.
Secrets are now embedded in values.yaml which is stored in git.

NOTE: This is a temporary solution. Future improvement should:
- Modify MCP charts to support existingSecret
- Or use SealedSecrets/SOPS-encrypted valuesFrom in Flux

All 16 MCP charts now ready for deployment via Flux.

platform/mcp-servers/helmrelease.yaml

@@ -27,11 +27,5 @@ spec:
       remediateLastFailure: true
     cleanupOnFail: true
 
-  valuesFrom:
-    - kind: ConfigMap
-      name: mcp-umbrella-values
-      optional: true
-
   values:
-    # Values from values.yaml will be automatically used
-    # Additional overrides can be placed here
+    # Values from values.yaml in git will be automatically used