fix: add stylus to CSS resolution cases and getAstGrepLang mapping

src/services/code-graph.ts

@@ -314,7 +314,7 @@ export function getAstGrepLang(ext: string): Lang | string | null {
     ".ts": Lang.TypeScript,
     ".tsx": Lang.Tsx,
     ".html": Lang.Html, ".htm": Lang.Html,
-    ".css": Lang.Css, ".scss": Lang.Css, ".sass": Lang.Css, ".less": Lang.Css,
+    ".css": Lang.Css, ".scss": Lang.Css, ".sass": Lang.Css, ".less": Lang.Css, ".styl": Lang.Css,
   };
   return map[ext] ?? null;
 }

src/services/graph-resolution.ts

@@ -39,7 +39,8 @@ export function resolveImport(
     case "css":
     case "scss":
     case "sass":
-    case "less": {
+    case "less":
+    case "stylus": {
       const cssExtensions = [".css", ".scss", ".sass", ".less", ".styl"];
       // CSS @import: ./variables.css, ../mixins.scss
       if (moduleSpecifier.startsWith(".")) {