### What problem does this PR solve?
As title.
### Type of change
- [x] Bug Fix (non-breaking change which fixes an issue)
<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit
* **Bug Fixes**
* Standardized the query parameter used when listing documents so
listings behave consistently across the web and client interfaces.
* Clarified the error message shown when a required dataset ID is
missing to give clearer guidance to users.
* **Tests**
* Updated test coverage to reflect the standardized dataset identifier
usage.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
---------
Signed-off-by: Jin Hai <haijin.chn@gmail.com>
### What problem does this PR solve?
Files /file API to RESTFul style.
### Type of change
- [x] Documentation Update
- [x] Refactoring
---------
Co-authored-by: writinwaters <cai.keith@gmail.com>
Co-authored-by: Liu An <asiro@qq.com>
### What problem does this PR solve?
Codecov’s coverage report shows that several RAGFlow code paths are
currently untested or under-tested. This makes it easier for regressions
to slip in during refactors and feature work.
This PR adds targeted automated tests to cover the files and branches
highlighted by Codecov, improving confidence in core behavior while
keeping runtime functionality unchanged.
### Type of change
- [x] Other (please describe): Test coverage improvement (adds/extends
unit and integration tests to address Codecov-reported gaps)
### 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
