### What problem does this PR solve?
The Profile **Name** field currently lacks application-level validation
and allows users to save excessively long names and unsupported special
characters.
While the database enforces a maximum length of 100 characters, neither
the frontend nor backend validates nickname format before persistence.
This can result in inconsistent user data, poor user experience, and UI
layout issues when long names wrap across multiple lines.
This PR introduces consistent frontend and backend validation for
profile names, enforces length and character constraints, provides clear
validation feedback, and prevents invalid values from being saved.
Fixes#15693
### Type of change
* [x] Bug Fix (non-breaking change which fixes an issue)
### What problem does this PR solve?
Manage and display memory datasets.
### Type of change
- [x] New Feature (non-breaking change which adds functionality)
### What problem does this PR solve?
- Replace hardcoded 255-byte file name length checks with
FILE_NAME_LEN_LIMIT constant
- Update error messages to show the actual limit value
- #8290
### Type of change
- [x] Refactoring
Co-authored-by: Kevin Hu <kevinhu.sh@gmail.com>
### What problem does this PR solve?
Change filename length limit from 128 to 256
### Type of change
- [x] Bug Fix (non-breaking change which fixes an issue)
Signed-off-by: Jin Hai <haijin.chn@gmail.com>
### What problem does this PR solve?
Test cases about dataset
### Type of change
- [x] Other (please describe): test cases
---------
Signed-off-by: jinhai <haijin.chn@gmail.com>
### What problem does this PR solve?
1. Remove unused code.
2. Move some codes from settings to constants
### Type of change
- [x] Refactoring
---------
Signed-off-by: jinhai <haijin.chn@gmail.com>
