### What problem does this PR solve?
1. Split dataset api to gateway and service, and modify web UI to use
restful http api.
2. Old KB releated APIs are commented.
### Type of change
- [x] Refactoring
### What problem does this PR solve?
Empty ids means no-op operation.
### Type of change
- [x] Bug Fix (non-breaking change which fixes an issue)
- [x] Documentation Update
- [x] Refactoring
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Co-authored-by: writinwaters <cai.keith@gmail.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)
