Fix: Switch the default theme from light mode to dark mode and improve some styles #9869 (#10552)

### 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)

web/src/components/data-pipeline-select/index.tsx

@@ -108,6 +108,7 @@ export function DataFlowSelect(props: IProps) {
                         {...field}
                         placeholder={t('dataFlowPlaceholder')}
                         options={options}
+                        triggerClassName="!bg-bg-base"
                       />
                     )}
                     {isMult && (