### What problem does this PR solve?

- Add comprehensive test suite for chunk operations including:
  - Test files for create, list, retrieve, update, and delete chunks
  - Authorization tests
  - Batch operations tests
- Update test configurations and common utilities
- Validate `important_kwd` and `question_kwd` fields are lists in
chunk_app.py
- Reorganize imports and clean up duplicate code

### Type of change

- [x] Add test cases

### What problem does this PR solve?

- Rename `api_key` fixture to `HttpApiAuth` across all test files
- Update all dependent fixtures and test cases to use new naming
- Maintain same functionality while improving naming clarity

The rename better reflects the fixture's purpose as an HTTP API
authentication helper rather than just an API key.

### Type of change

- [x] Refactoring

### What problem does this PR solve?

- Consolidate HTTP API test fixtures using batch operations
(batch_add_chunks, batch_create_chat_assistants)
- Fix fixture initialization order in clear_session_with_chat_assistants
- Add new SDK API test suite for session management
(create/delete/list/update)

### Type of change

- [x] Add test cases
- [x] Refactoring

### What problem does this PR solve?

fix document typo in test

### Type of change

- [x] Typo

### What problem does this PR solve?

Move test cases only - CI still runs tests under sdk/python

### Type of change

- [x] Refactoring

### 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?

change variable for ZHIPU_AI_API_KEY

### Type of change

- [x] Update test case

### 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?

This PR introduces Pydantic-based validation for the delete dataset HTTP
API, improving code clarity and robustness. Key changes include:

1. Pydantic Validation
2. Error Handling
3. Test Updates
4. Documentation Updates

### Type of change

- [x] Documentation Update
- [x] Refactoring

### What problem does this PR solve?

Configure test case priorities to reduce CI execution time

### Type of change

- [x] Test cases update

### What problem does this PR solve?

cover [create session with chat
assistant](https://ragflow.io/docs/dev/http_api_reference#create-session-with-chat-assistant)
endpoints

### Type of change

- [x] add test cases

### What problem does this PR solve?

cover [create chat
assistant](https://ragflow.io/docs/v0.17.2/http_api_reference#create-chat-assistant)
endpoints

### Type of change

- [x] add 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?

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

### Type of change

- [x] update test cases

### What problem does this PR solve?

cover [download docments
endpoints](https://ragflow.io/docs/dev/http_api_reference#download-document)

### Type of change

- [x] add test cases

### What problem does this PR solve?

cover upload docments endpoints

### Type of change

- [x] add test cases