Remove dead dual-publish wiring: rewrite script + deprecation warning

Delete scripts/rewrite-packages-to-hexclave.ts and the SDK deprecation-warning
side-effect module (plus its import in the template entrypoint). With packages
renamed to @hexclave/* in source, no @stackframe/* artifact is built, so the
runtime warning has nothing to detect and the publish-time rewrite step is gone.

Author: BilalG1

packages/template/src/index.ts

@@ -1,9 +1,3 @@
-// Side-effect import — fires once-per-process @stackframe/* deprecation warning at SDK load time.
-// In packages published as @hexclave/*, scripts/rewrite-packages-to-hexclave.ts rewrites the
-// build-time sentinel inside dist/ (`js @stackframe/<pkg>@<ver>` → `js @hexclave/<new>@<ver>`),
-// so the @stackframe/-prefixed check in deprecation-warning.ts short-circuits there.
-import "./internal/deprecation-warning";
-
 export * from './lib/stack-app';
 export { getConvexProvidersConfig } from "./integrations/convex";
 // Hexclave aliases and legacy Stack* names — @deprecated JSDoc lives on the original