Use Workerd for local development

.changeset/nervous-weeks-tap.md

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+---
+'@shopify/cli-hydrogen': patch
+---
+
+Adjust behavior of `h2 preview` command around environment variables to be more consistent with `h2 dev` command.

.changeset/silver-bikes-reply.md

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+---
+'@shopify/hydrogen': patch
+---
+
+The `error.cause` property throw from the Storefront client is now stringified.

.changeset/warm-terms-try.md

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+---
+'@shopify/cli-hydrogen': minor
+---
+
+Add `--worker-unstable` flag to `h2 dev` and `h2 preview` commands. This flag enables the use of the new experimental worker runtime for local development, which is closer to Oxygen production than the current Node.js sandbox. Please report any issues you encounter with this flag.