Refactor:Standardize image conf and add private registry support (#9496)

- Unified configuration format: All services now use the same image
configuration structure for consistency.

- Private registry support: Added imagePullSecrets to enable pulling
images from private registries.

- Per-service flexibility: Each service can override image-related
parameters independently.

### What problem does this PR solve?

_Briefly describe what this PR aims to solve. Include background context
that will help reviewers understand the purpose of the PR._

### Type of change

- [ ] Bug Fix (non-breaking change which fixes an issue)
- [ ] New Feature (non-breaking change which adds functionality)
- [ ] Documentation Update
- [ ] Refactoring
- [ ] Performance Improvement
- [ ] Other (please describe):

helm/templates/ragflow.yaml

@@ -25,9 +25,21 @@ spec:
         checksum/config-env: {{ include (print $.Template.BasePath "/env.yaml") . | sha256sum }}
         checksum/config-ragflow: {{ include (print $.Template.BasePath "/ragflow_config.yaml") . | sha256sum }}
     spec:
+      {{- if or .Values.imagePullSecrets .Values.ragflow.image.pullSecrets }}
+      imagePullSecrets:
+        {{- with .Values.imagePullSecrets }}
+        {{- toYaml . | nindent 8 }}
+        {{- end }}
+        {{- with .Values.ragflow.image.pullSecrets }}
+        {{- toYaml . | nindent 8 }}
+        {{- end }}
+      {{- end }}
       containers:
       - name: ragflow
-        image: {{ .Values.env.RAGFLOW_IMAGE }}
+        image: {{ .Values.ragflow.image.repository }}:{{ .Values.ragflow.image.tag }}
+        {{- with .Values.ragflow.image.pullPolicy }}
+        imagePullPolicy: {{ . }}
+        {{- end }}
         ports:
           - containerPort: 80
             name: http