Resolve bundled artifacts without a world-age trampoline

[quinnj]

Summary

Resolve the tzjdata artifact at runtime without embedding a depot-specific precompile path or relying on the world-age trampoline emitted by the artifact string macro. This keeps artifact lookup relocatable for bundled system images and trim-compiled executables.

Implementation

• Read and store the artifact hash from Artifacts.toml during precompilation.
• Resolve that hash against the runtime artifact directories when artifact_dir() is called.
• Return the first existing artifact directory, while preserving the normal first-candidate fallback when the artifact has not yet been materialized.

Validation

• TZJData tests pass on Julia 1.12.5 (3/3).
• TZJData tests pass on JuliaC 1.14-dev (3/3).
• The LeagueEasy trim-safe workload reaches TZJData initialization with zero verifier errors.
• A bundled executable resolves the artifact correctly after relocation.
• Upstream CI passes on Julia 1.6, Julia 1.x, and Julia nightly, including the artifact check.

Open Question

The lookup follows the normal artifact-directory search order, but it does not yet apply custom Overrides.toml mappings. This remains a draft while the expected override semantics are reviewed.

Co-authored by Codex