ci(release): re-enable x86_64-apple-darwin target post-V0

[aram-devdocs]

Dropped from cargo-dist matrix to unblock V0 ship after GitHub's macos-13 runner pool starved (single Build x86_64-apple-darwin job queued >50min blocking release.yml run 25494044353).

Current coverage

After this drop the V0 install matrix is:

• macOS Apple Silicon (aarch64-apple-darwin) — covers every Mac shipped since 2020
• Linux x86_64 / ARM64 / musl
• Windows x86_64

Intel Mac users (Apple silenced Intel sales in 2023; tail user count) can still cargo install plumb-cli from crates.io.

Re-enable acceptance

• Restore x86_64-apple-darwin in dist-workspace.toml and .github/workflows/release.yml matrix.
• Confirm macos-13 runner pool is healthy (or migrate to native macos-14 / Apple Silicon cross-compile via cargo zigbuild).
• Verify cargo-dist build for that target succeeds against a tag.

Why now

V0 release pipeline has spent 4+ hours iterating on publish failures (#248-#266). All other channels (crates.io, brew, npm, curl-installer) are blocked behind one queued runner. Pragmatic to ship with 5 native targets + cargo install fallback for Intel Macs and revisit when runner pool recovers.