### 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?
Changed test priorities in multiple test files, downgrading from p1 to
p2 and p2 to p3.
### Type of change
- [x] Bug Fix (non-breaking change which fixes an issue)
### What problem does this PR solve?
Write testcase for message web apis.
### Type of change
- [x] New Feature (non-breaking change which adds functionality)
---------
Co-authored-by: Kevin Hu <kevinhu.sh@gmail.com>
### What problem does this PR solve?
Testcase for get_message_content api.
### Type of change
- [x] New Feature (non-breaking change which adds functionality)
---------
Co-authored-by: Kevin Hu <kevinhu.sh@gmail.com>
### What problem does this PR solve?
Web API testcase for list_messages, get_recent_message.
### Type of change
- [x] New Feature (non-breaking change which adds functionality)
---------
Co-authored-by: Kevin Hu <kevinhu.sh@gmail.com>
