fix(studio): guard import.meta.env for non-Vite consumers

manualEditingAvailability.ts unconditionally reads `import.meta.env`.
That's a Vite-only extension; in plain ESM hosts (Next.js / Turbopack,
Node, jest in some configs) `import.meta` exists but `import.meta.env`
is `undefined`. Reading any property off undefined throws at module
evaluation time, so the studio fails to load the moment a non-Vite
host imports anything from `@hyperframes/studio`.

Guard the read so the module is loadable everywhere; outside Vite,
every flag falls back to its declared default, preserving Vite
behavior.

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

Author: terencecho

packages/studio/src/components/editor/manualEditingAvailability.ts

@@ -27,7 +27,15 @@ export function resolveStudioBooleanEnvFlag(
   return fallback;
 }
 
-const env = import.meta.env as StudioFeatureFlagEnv;
+// Guard `import.meta.env` for non-Vite consumers. The studio is consumable
+// from Next.js demos (e.g. hyperframes-internal/demo-next) and other ESM
+// hosts where `import.meta` exists but `import.meta.env` is undefined —
+// reading any property off `undefined` would crash at module evaluation
+// time. In non-Vite hosts every flag falls back to its declared default,
+// matching prior intent. Vite consumers are unaffected.
+const env = ((typeof import.meta !== "undefined"
+  ? (import.meta as { env?: unknown }).env
+  : undefined) ?? {}) as StudioFeatureFlagEnv;
 
 export const STUDIO_PREVIEW_MANUAL_EDITING_ENABLED = resolveStudioBooleanEnvFlag(
   env,