build(deps-dev): bump sass from 1.77.6 to 1.83.4 in /webapp

Bumps [sass](https://github.com/sass/dart-sass) from 1.77.6 to 1.83.4.
- [Release notes](https://github.com/sass/dart-sass/releases)
- [Changelog](https://github.com/sass/dart-sass/blob/main/CHANGELOG.md)
- [Commits](https://github.com/sass/dart-sass/compare/1.77.6...1.83.4)

---
updated-dependencies:
- dependency-name: sass
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

webapp/package.json

@@ -39,7 +39,7 @@
     "npm-run-all": "^4.1.5",
     "prettier": "^3.4.2",
     "pulltorefreshjs": "^0.1.22",
-    "sass": "=1.77.6",
+    "sass": "=1.83.4",
     "terser": "^5.37.0",
     "typescript": "~5.6.3",
     "vite": "^6.0.7",