### What problem does this PR solve?

- Removed hardcoded Zhipu API key from codebase
- New requirement: Tests now require ZHIPU_AI_API_KEY environment
variable
  Example: export ZHIPU_AI_API_KEY=your_api_key_here

### Type of change

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

### What problem does this PR solve?

change default models to buildin models
https://github.com/infiniflow/ragflow/issues/7774

### Type of change

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

### What problem does this PR solve?

use environment variable for ZHIPU_AI_API_KEY

### Type of change

- [x] Test update

### What problem does this PR solve?

Skip test case for PR #6443

### Type of change

- [x] update test cases

### What problem does this PR solve?

 Refactor test fixtures and test cases

### Type of change

- [ ] Refactoring test cases

### What problem does this PR solve?

1. add test cases
2. integrate workflows/tests.yml into CI pipeline

### Type of change

- [x] add testcases

### What problem does this PR solve?

Add license statement.

### Type of change

- [x] Refactoring

Signed-off-by: Jin Hai <haijin.chn@gmail.com>

### What problem does this PR solve?

Fix errors detected by Ruff

### Type of change

- [x] Refactoring

### What problem does this PR solve?

Fix test cases

### Type of change

- [x] Other (please describe): Fix error cases

---------

Signed-off-by: jinhai <haijin.chn@gmail.com>

### What problem does this PR solve?

1. Read KB list path parameter, page_number and page_size, which type
isn't int
2. Add cases on create / list / delete datasets.

### Type of change

- [x] Bug Fix (non-breaking change which fixes an issue)
- [x] Test cases

Signed-off-by: jinhai <haijin.chn@gmail.com>

### What problem does this PR solve?

Add tests for frontend API

### Type of change

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

---------

Co-authored-by: liuhua <10215101452@stu.ecun.edu.cn>

### What problem does this PR solve?

Unified API response json schema

### Type of change

- [x] Refactoring

### What problem does this PR solve?

Add test for CI

### Type of change

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

Co-authored-by: liuhua <10215101452@stu.ecun.edu.cn>

### What problem does this PR solve?

Test Cases

### Type of change

- [x] Refactoring

Co-authored-by: liuhua <10215101452@stu.ecun.edu.cn>