fix(cli): pass 'dir' type to symlinkSync for Windows compatibility

On Windows, symlinkSync without a type argument auto-detects by
stat-ing the target relative to process.cwd(), not the link's parent
directory. This causes directory symlinks to be created as file type,
breaking skill linking. Passing 'dir' explicitly fixes this (ignored
on macOS/Linux).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: Brooooooklyn

packages/cli/src/utils/skills.ts

@@ -98,7 +98,7 @@ function linkSkills(
     }
 
     try {
-      symlinkSync(relativeTarget, linkPath);
+      symlinkSync(relativeTarget, linkPath, 'dir');
     } catch (err: unknown) {
       prompts.log.warn(`  ${skill.name} — failed to create symlink: ${(err as Error).message}`);
       continue;