The Windows UI needs winsafe, whose current release requires rustc 1.87. The
alternative was pinning winsafe back to an older release, which would bake a
stale API surface into a brand-new UI permanently to dodge one minor version.
The pin's purpose is to sit BELOW the Mac default so clippy drift is caught
locally before CI, not to stay on 1.86 specifically, so 1.87 preserves the
discipline exactly.
Verified before moving anything, not after: `cargo +1.87 clippy -- -D warnings`
and `cargo +1.87 fmt --check` are clean across all eight repos, and the full
precommit gate (fmt + clippy + tests) passes on libfreemkv, autorip, bdemu,
freemkv-engine and freemkv-keysources. Zero new lints, zero formatting drift.