feat(astro): add Astro language support and editor mode (#712)

Astro files get their own language: TypeScript frontmatter, HTML template with TSX expressions in text and tags, TypeScript scripts, astro-ls and oxlint servers, and file-type icons.

package.json

@@ -22,6 +22,7 @@
     "gen:windows-icons": "node scripts/gen-windows-icons.ts",
     "gen:angular-grammar": "lezer-generator src/editor/core/cm/angular/angular.grammar --typeScript -o src/editor/core/cm/angular/parser.ts",
     "gen:jsp-grammar": "lezer-generator src/editor/core/cm/jsp/jsp.grammar --typeScript -o src/editor/core/cm/jsp/parser.ts",
+    "gen:astro-grammar": "lezer-generator src/editor/core/cm/astro/astro.grammar --typeScript -o src/editor/core/cm/astro/parser.ts",
     "gen:theme-docs": "node scripts/theme/gen-docs.ts",
     "theme:import-intellij": "node scripts/theme/import-intellij-theme.ts",
     "dev:app": "node scripts/tauri.ts dev --config src-tauri/tauri.dev.conf.json",