### What problem does this PR solve?
Feat: Replace color variables according to design draft #3221
### Type of change
- [x] New Feature (non-breaking change which adds functionality)
### What problem does this PR solve?
Replace Avatar with RAGFlowAvatar component for knowledge base and
agent, optimize Agent template page, and modify bugs in knowledge base
#3221
### Type of change
- [x] Bug Fix (non-breaking change which fixes an issue)
### What problem does this PR solve?
Feat: Using IconFont as an additional icon library #3221
### Type of change
- [x] New Feature (non-breaking change which adds functionality)
### What problem does this PR solve?
Feat: Modify background color of Card #3221
### Type of change
- [x] New Feature (non-breaking change which adds functionality)
### What problem does this PR solve?
Feat: Modify the segmented component style #3221
### Type of change
- [x] New Feature (non-breaking change which adds functionality)
### What problem does this PR solve?
Feat: Adjust the style of the home page #3321
### Type of change
- [x] New Feature (non-breaking change which adds functionality)
### What problem does this PR solve?
Feat: Bind data to the agent module of the home page #3221
### Type of change
- [x] New Feature (non-breaking change which adds functionality)
