chore(build): bump sccache to 0.16.0

[matthewgrossman]

Summary

Bump sccache to 0.16.0 to pick up the upstream compiler-resolution fix needed by the Docker E2E cargo-zigbuild path. The failure occurs before the smoke tests run, while cross-compiling openshell-sandbox for aarch64-unknown-linux-musl.

Failure details

mise run e2e:docker builds the gateway and CLI, then stages the Docker supervisor with cargo zigbuild. The mise environment globally sets RUSTC_WRAPPER=sccache, so every Rust compiler invocation passes through sccache.

With sccache 0.14.0, sccache could select the configured wrapper again while trying to resolve the real compiler behind cargo-zigbuild and its generated Zig compiler shim. Compiler discovery then failed and sccache surfaced the result as an unsupported compiler:

sccache: error: Compiler not supported: "error: unable to create compilation: AccessDenied\n"

This aborts the supervisor cross-compile before Docker E2E tests start. Setting SCCACHE_DISABLE=1 does not avoid the failure because it disables caching behavior but does not remove Cargo’s RUSTC_WRAPPER; Cargo still launches sccache.

Why 0.16.0 fixes it

The official sccache 0.16.0 release notes list the relevant correctness change: “avoid the sccache wrapper when resolving the real compiler” (mozilla/sccache#2720). That prevents wrapper selection from interfering with discovery of cargo-zigbuild’s actual compiler command.

Related Issue

No issue required: localized build-tool maintenance fix for a known upstream defect.

Changes

• Pin sccache 0.16.0 in mise.toml
• Regenerate sccache lock entries and checksums for macOS arm64, Linux arm64, and Linux x64
• Preserve cargo-zigbuild 0.22.3 and the Linux x64 asset-selection override

Testing

• mise run pre-commit passes
• Clean aarch64-unknown-linux-musl supervisor build passes with RUSTC_WRAPPER=sccache
• mise run e2e:docker passes

Checklist

• Follows Conventional Commits
• Commits are signed off (DCO)
• Architecture docs updated (not applicable; build-tool pin only)

[github-actions]

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