chore(deps): dedupe pnpm-lock.yaml (#1901)

I ran `pnpm dedupe` 🧑‍💻

<!-- CURSOR_SUMMARY -->
---

> [!NOTE]
> **Medium Risk**
> Lockfile-only, but it bumps the core Sanity Studio `next` dependency
across all plugins, which can surface compatibility regressions.
> 
> **Overview**
> Updates `pnpm-lock.yaml` so packages pinned to the Sanity `next` tag
resolve from **`6.9.2-next.75` → `6.9.3-next.3`** across the monorepo.
> 
> Also replaces `@sanity-labs/ui-poc` with `@sanity/ui@5.0.0-alpha.3`
(as Sanity’s `ui5` dependency) and bumps `@sanity/presentation-comlink`
to `2.2.3`. No package manifests or source changes.
> 
> <sup>Reviewed by [Cursor Bugbot](https://cursor.com/bugbot) for commit
43ebe4e. Bugbot is set up for automated
code reviews on this repo. Configure
[here](https://www.cursor.com/dashboard/bugbot).</sup>
<!-- /CURSOR_SUMMARY -->

Co-authored-by: squiggler-app[bot] <265501495+squiggler-app[bot]@users.noreply.github.com>

Author: squiggler-app[bot]