fix: revert app/sdks exclusion (not present in CI)

The app/sdks directory is gitignored and doesn't exist in CI. Removing
the exclusion to avoid PHPStan failing on a non-existent path.

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

phpstan.neon

@@ -14,5 +14,4 @@ parameters:
     - vendor/swoole/ide-helper
   excludePaths:
     - tests/resources
-    - app/sdks