[iAziz786]

Summary

Raise the declared toolchain from Rust 1.99.0 to stable 1.99.1 in every place that states it:

 Cargo.toml
-  rust-version = "1.99.0"
+  rust-version = "1.99.1"

 .github/workflows/release.yml
-  RUST_TOOLCHAIN_VERSION: "1.99.0"
+  RUST_TOOLCHAIN_VERSION: "1.99.1"

 README.md
-  You need Rust 1.99.0 or newer.
+  You need Rust 1.99.1 or newer.

 skills/selfhostdev/SKILL.md
-  ... Rust 1.99.0+ ...
+  ... Rust 1.99.1+ ...

 .github/workflows/rust.yml
+  read rust-version from Cargo.toml
+  install that toolchain before build/test

The Rust CI job used the runner image's preinstalled stable (1.99.0), which rejects a crate declaring 1.99.1. It now installs the version Cargo.toml declares, so the job always proves the advertised floor compiles instead of drifting behind it.

Evidence

• Before: cargo build on the runner — error: rustc 1.99.0 is not supported by the following package: selfhost-cli@0.3.2 requires rustc 1.99.1 (run 39410711870).
  After: Rust job passes in 1m34s (run 39410845615).
• cargo test locally on 1.99.1 — 7 targets, 245 passed, 0 failed (174 unit, 18, 17, 15, 10, 6, 5).
• cargo clippy --all-targets — 0 warnings, 0 errors.
• cargo fmt --check — only the 7 pre-existing drift files named in AGENTS.md; none touched here.
• cargo metadata reports "rust_version":"1.99.1"; rg "1\.99\.0" finds no stale references.
• Smoke: target/debug/selfhost --version prints selfhost 0.3.2.

Merge Danger

Door: two-way — revert restores the 1.99.0 floor.

Blast Radius: build-only.

Raising rust-version drops 1.99.0 from the supported compilers for source builds. Anyone on 1.99.0 must update to build; published binaries are unaffected because they are built by the pinned release toolchain. CI now downloads the declared toolchain on every run instead of reusing the image's stable.