feat(compiler): resolve .tsx imports and tag them as islands

.wrn keeps resolution priority so existing components are unaffected
when a .tsx file shares their name.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

packages/compiler/src/import-resolver.ts

@@ -11,6 +11,8 @@ export interface ImportResolverOptions {
 export interface ResolvedImport {
   declaration: StructuredImportDecl;
   resolved?: string;
+  /** `.tsx` imports are React islands, not `.wrn` components. */
+  kind?: "island";
   diagnostic?: { code: string; message: string; severity: "error" | "warning" };
 }
 
@@ -21,9 +23,11 @@ function candidates(path: string): string[] {
         path,
         `${path}.wrn`,
         `${path}.ts`,
+        `${path}.tsx`,
         `${path}.d.ts`,
         join(path, "index.wrn"),
         join(path, "index.ts"),
+        join(path, "index.tsx"),
       ];
 }
 
@@ -56,7 +60,12 @@ export function resolveWrnImport(
       return false;
     }
   });
-  if (found) return { declaration, resolved: realpathSync(found) };
+  if (found) {
+    const resolved = realpathSync(found);
+    return resolved.endsWith(".tsx")
+      ? { declaration, resolved, kind: "island" as const }
+      : { declaration, resolved };
+  }
   const severity = (options.mode ?? "compatible") === "explicit" ? "error" : "warning";
   return {
     declaration,