### What problem does this PR solve?
This PR adds missing HTTP API test coverage for dataset
graph/GraphRAG/RAPTOR tasks, metadata summary, chat completions, agent
sessions/completions, and related questions. It also introduces minimal
HTTP test helpers to exercise these endpoints consistently with the
existing suite.
### Type of change
- [x] Other (please describe): Test coverage (HTTP API tests)
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Co-authored-by: Liu An <asiro@qq.com>
### What problem does this PR solve?
- Add new test suite for document app with
create/list/parse/upload/remove tests
- Update API URLs to use version variable from config in HTTP and web
API tests
### Type of change
- [x] Add test cases
### What problem does this PR solve?
- Move common constants (HOST_ADDRESS, INVALID_API_TOKEN, etc.) to
configs.py
- Update test imports to use centralized configs
- Clean up duplicate constant definitions across test files
This improves maintainability by centralizing configuration.
### Type of change
- [x] Refactoring test case