chore: mark v0.4 schema as experimental

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

src/schemas/0.4.ts

@@ -1,4 +1,5 @@
 // v0.4: Adds UV runtime support for Python extensions
+// NOTE: This schema version is experimental and subject to change.
 import * as z from "zod";
 
 export const MANIFEST_VERSION = "0.4";

src/schemas_loose/0.4.ts

@@ -1,3 +1,5 @@
+// v0.4: Adds UV runtime support for Python extensions
+// NOTE: This schema version is experimental and subject to change.
 import * as z from "zod";
 
 export const MANIFEST_VERSION = "0.4";