fix(repo-identity): use native realpath on Windows to resolve 8.3 short paths (#1960)

Use realpathSync.native() on Windows in canonicalizeExistingPath to resolve
8.3 short names (RUNNER~1 → runneradmin). Fixes isInheritedRepo path
comparison failures on Windows CI.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/resources/extensions/gsd/repo-identity.ts

@@ -164,7 +164,8 @@ function getRemoteUrl(basePath: string): string {
  */
 function canonicalizeExistingPath(path: string): string {
   try {
-    return realpathSync(path);
+    // Use native realpath on Windows to resolve 8.3 short paths (e.g. RUNNER~1)
+    return process.platform === "win32" ? realpathSync.native(path) : realpathSync(path);
   } catch {
     return resolve(path);
   }