chore(smartcontract): use strum instead of enumerating all errors

[bgm-malbeclabs]

Summary of Changes

I noticed that AccessPassInUse wasn't present in the test. strum automatically generates the error variants.

Closes #2852

Testing Verification

• Tests pass

[Copilot]

Pull request overview

Refactors the smart contract error conversion test to iterate over DoubleZeroError variants automatically via strum, reducing the chance of missing variants in manual lists.

Changes:

• Derive EnumIter for DoubleZeroError in test builds and iterate over variants in the conversion test.
• Add strum / strum_macros workspace dependencies and include them in the program crate.

Reviewed changes

Copilot reviewed 3 out of 4 changed files in this pull request and generated 2 comments.

File	Description
smartcontract/programs/doublezero-serviceability/src/error.rs	Switches the error conversion test from a manual variant list to strum-driven iteration.
smartcontract/programs/doublezero-serviceability/Cargo.toml	Adds strum dependencies for the program crate to support test-only iteration.
Cargo.toml	Pins workspace versions for strum and strum_macros.

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