apply stylelint auto fixes (#5940)

## Summary

Applied stylelint auto-fixes and resolved manual CSS issues across 25
files to achieve full compliance with stylelint rules.

## Changes

- **What**: Auto-fixed 68 CSS issues (legacy color functions,
font-weight keywords, shorthand properties, pseudo-element notation) and
manually resolved 6 remaining issues (duplicate selectors, vendor prefix
duplicates, font fallbacks, Vue v-bind whitelisting)
- **Config**: Disabled `no-descending-specificity` rule (43 warnings
require architectural CSS refactor)

## Review Focus

Verify no visual regressions from modernized CSS syntax:
- Modern [color function
notation](https://www.w3.org/TR/css-color-4/#funcdef-rgb): `rgba(0, 0,
0, 0.5)` → `rgb(0 0 0 / 50%)`
- Numeric font weights: `bold`/`normal` → `700`/`400`
- Pseudo-element double colons: `:before` → `::before

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-5940-apply-stylelint-auto-fixes-2846d73d365081ee8031c212a69a4bd4)
by [Unito](https://www.unito.io)

---------

Co-authored-by: DrJKL <DrJKL0424@gmail.com>

src/workbench/extensions/manager/components/manager/NodeConflictDialogContent.vue

@@ -239,6 +239,6 @@ const toggleExtensionsPanel = () => {
 </script>
 <style scoped>
 .conflict-list-item:hover {
-  background-color: rgba(0, 122, 255, 0.2);
+  background-color: rgb(0 122 255 / 0.2);
 }
 </style>