chore: add changeset for dropping default studio app load

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: os-zhuang

.changeset/drop-studio-app-default-load.md

@@ -0,0 +1,11 @@
+---
+'@objectstack/cli': patch
+'@objectstack/plugin-dev': patch
+---
+
+`os dev` / `os start` / `os serve` no longer default-load the `@objectstack/studio` app package.
+
+The console ships a dedicated Studio surface at `/_console/studio/<package-id>/<pillar>`,
+so Studio no longer needs to exist as a navigable app tile in the home "Your apps" list.
+The `@objectstack/studio` package is unchanged and can still be registered explicitly;
+Setup and Account remain default-loaded (ADR-0048 one-app-per-package mechanism).