feat(sdk): file-backed fs adapter + setTiming GSAP sync; sdk-playground workspace (#1458)

* feat(sdk): file-backed fs adapter + setTiming GSAP-script sync; add sdk-playground

* fix(sdk): address PR #1423 review — oxfmt, PersistVersionEntry contract, race, comments

- bunx oxfmt packages/sdk-playground/index.html (unblocks CI)
- PersistVersionEntry.content is now optional; HTTP adapter omits it for lazy-load
- fs adapter: monotonic key (Date.now-NNNN) + per-path write serialization via promise chain
- mutate.ts: fix wrong comment on GSAP sync reason; add caveat to "pre-parse once" note

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

Co-authored-by: Miguel Ángel <miguel07alm@protonmail.com>

* fix(core): oxfmt gsapSerialize.ts — unblocks Preflight across stack

Pre-existing format issue on the base; fixing here to unblock CI.

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

Co-authored-by: Miguel Ángel <miguel07alm@protonmail.com>

* chore: update bun.lock for sdk-playground workspace

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

---------

Co-authored-by: Miguel Ángel <miguel07alm@protonmail.com>
Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

packages/sdk-playground/package.json

@@ -0,0 +1,17 @@
+{
+  "name": "@hyperframes/sdk-playground",
+  "private": true,
+  "type": "module",
+  "scripts": {
+    "dev": "vite",
+    "build": "vite build"
+  },
+  "dependencies": {
+    "@hyperframes/core": "workspace:*",
+    "@hyperframes/sdk": "workspace:*",
+    "gsap": "^3.15.0"
+  },
+  "devDependencies": {
+    "vite": "^6.4.2"
+  }
+}