### What problem does this PR solve?
Fix: Switch the default theme from light mode to dark mode and improve
some styles #9869
-Update UI component styles such as input boxes, tables, and prompt
boxes
-Optimize login page layout and style details
-Revise some of the wording, such as uniformly changing "data flow" to
"pipeline"
-Adjust the parser to support the markdown type
### Type of change
- [x] Bug Fix (non-breaking change which fixes an issue)
### What problem does this PR solve?
Fix: Added table of contents extraction functionality and optimized form
item layout #9869
- Added `EnableTocToggle` component to toggle table of contents
extraction on and off
- Added multiple parser configuration components (such as naive, book,
laws, etc.), displaying different parser components based on built-in
slicing methods
### Type of change
- [x] Bug Fix (non-breaking change which fixes an issue)