feat(result): add unwrap and expect functions

[coderdan]

Summary

Adds Rust-inspired unwrap and expect escape hatches to @byteslice/result, for the cases where a caller knows an operation should have succeeded and just wants the underlying data.

• unwrap(result) — returns the success data, or re-throws the failure's underlying Error.
• expect(result, message) — returns the success data, or throws a new Error(message, { cause }), preserving the original error's stack trace via cause (consistent with how the existing docs treat errors).

Both handle both FailureOption shapes (a bare Error and the { error: Error } custom-failure object).

Design note

Result is modelled as a plain discriminated union (not a class), and the public API is free functions like withResult. To stay consistent, these are free functions (unwrap(result)) rather than methods (result.unwrap()) — keeping Result a plain, serializable object. If you'd prefer method-style chaining, that's a larger design shift worth discussing separately.

A small internal isSuccess type guard is used because, with a generic failure type F, TypeScript won't narrow the union on result.failure === undefined directly.

Testing

• Added unit tests covering success, failure re-throw, custom-failure unwrapping, expect's message, and cause preservation.
• bun test (13 pass), biome ci, cspell, and tsup build all pass.

Changeset

Included a minor changeset (new backward-compatible features).

[changeset-bot]

🦋 Changeset detected

Latest commit: e021f2e

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 3 packages

Name	Type
@byteslice/result	Minor
@byteslice/events	Patch
@byteslice/playground	Patch

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[dylnslck]

🚀