chore: Enforce import order via @ianvs/prettier-plugin-sort-imports (#2542)

prettier.config.js

@@ -11,6 +11,22 @@ const config = {
   printWidth: 89,
   tabWidth: 2,
   embeddedLanguageFormatting: 'auto',
+
+  // Sort imports as part of formatting so editor-on-save and CI agree. Three groups
+  // separated by a blank line: node built-ins, then non-relative (third-party), then
+  // relative. Empty strings insert the blank line between groups; sort is
+  // case-insensitive. Side-effect imports are left in place as sort barriers to
+  // preserve their evaluation order. Setting the TypeScript version lets same-module
+  // type and value imports combine into a single statement with an inline `type`.
+  plugins: ['@ianvs/prettier-plugin-sort-imports'],
+  importOrder: ['<BUILTIN_MODULES>', '', '<THIRD_PARTY_MODULES>', '', '^[.]'],
+  importOrderTypeScriptVersion: '5.8.3',
+
+  // The codebase compiles with tsconfig `experimentalDecorators` (Lit's
+  // `@customElement`/`@property`/etc.), so babel must parse the legacy decorator
+  // proposal; without this it throws on decorated classes and silently skips sorting
+  // those files.
+  importOrderParserPlugins: ['typescript', 'decorators-legacy'],
 };
 
 export default config;