- 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):

### What problem does this PR solve?

Switch to Kubernetes StatefulSet resources for MySQL, Minio and vector
DB since these are stateful application components. This makes
operations such as helm upgrade smoother since the default container
update strategy becomes a sequential rolling update of each pod.

Also fixes a bug in the name template for the Minio stateful set
resource to align it with the naming convention used for other
components.

### Type of change

- [X] Bug Fix (non-breaking change which fixes an issue)

Modified the chart to retain persistent volumes by default when the
chart is uninstalled, following established best practices in the Helm
community (e.g., Bitnami charts)

### What problem does this PR solve?

Previously, deleting the helm chart would automatically remove all
persistent data, which poses a risk of accidental data loss.

### Rationale

This change aligns with industry standards to safeguard data by
requiring explicit action to remove persistence, rather than making
deletion the default behavior.

### Impact: 

Users who intentionally want to remove persistent data will need to do
so manually or by setting appropriate flags during chart uninstallation.

### Type of change

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

### What problem does this PR solve?

The initial Helm chart implementation added in #3815 suffers from an
issue where the 5GB data volume for the SQL DB is filled up with
[binlog](https://dev.mysql.com/doc/refman/8.4/en/binary-log.html) files
after just a few days. Since the app uses a non-replicated SQL DB config
I think it makes sense to disable the binlog in the SQL DB container.
This is achieved by simply adding the required argument to the container
startup command.

### Type of change

- [X] Bug Fix (non-breaking change which fixes an issue)

### What problem does this PR solve?

Add's a Helm chart for deploying RAGFlow on Kubernetes. 

Closes #864. 

### Type of change

- [X] New Feature (non-breaking change which adds functionality)