make install from a fresh clone fails when rustup's default is older than the workspace MSRV, and the error names xtask #29

What happened

From a fresh clone, on a machine whose rustup default was 1.94.0:

$ git clone https://github.com/tobi/disktree && cd disktree && make install
cargo xtask bundle
    Updating crates.io index
error: rustc 1.94.0 is not supported by the following package:
  xtask@0.10.1 requires rustc 1.97
make: *** [install] Error 101

Nothing is wrong with xtask. [workspace.package] rust-version = "1.97"
(Cargo.toml:8) is inherited by xtask/Cargo.toml via
rust-version.workspace = true, and .cargo/config.toml aliases
cargo xtask to cargo run --package xtask --, so xtask is the first
package in the build graph and the one cargo names. Cargo rejects the whole
workspace before compiling anything, so the failure arrives with no useful
platform, dependency or file context.

Why a fresh clone hits it

CI pins 1.97 (.github/workflows/{ci,release}.yml), the README says "Rust 1.97
or newer", but nothing provisions that toolchain for people building from
source. There is no rust-toolchain.toml, so a stale rustup default is a hard
failure rather than a nudge — and rustup update is not something the error
message or the README asks for at that point.

The 1.97 floor looks over-declared

No dependency in Cargo.lock sets rust-version (checked gpui-pre,
gpui-kit, gpui-base, gpui-pre-platform, gpui-pre-apple,
gpui-omarchy). Building the workspace with the MSRV check bypassed:

std::hint::cold_path is unstable in 1.94 and stable by 1.95, so the real floor
appears to be 1.95, not 1.97. That matters for anyone on a distro-packaged
cargo, which ignores rust-toolchain.toml entirely and can only be helped by
lowering the declared MSRV.

Caveat on that evidence: it is macOS/aarch64 only. The Linux path was not built
locally, so 1.95 on Linux is unverified.

Two things to decide

1. Provisioning — a rust-toolchain.toml pinning 1.97 (opened as a PR)
   makes rustup fetch the right toolchain on the first build, whatever
   rustup default says. It cannot change update-to-update behaviour of the
   gate either, since it pins the version CI already pins.
2. The floor — keep 1.97 deliberately, or lower rust-version to the
   verified 1.95 so distro-cargo builders are not locked out. Your call; the
   PR only does (1) so as not to declare a floor from one platform's evidence.