Align just ci with CI pipeline

[NotAProfDev]

Summary

The just ci recipe introduced in #7 does not fully match the steps in .github/workflows/ci.yml. This means a PR can pass just ci locally but still fail on CI.

Gaps

Check	CI	just ci
cargo fmt --all -- --check	✅	❌ missing
--all-features on check/clippy/test	✅	❌ missing
cargo doc with RUSTDOCFLAGS="-D warnings"	✅	❌ missing

Additionally, the .githooks/pre-commit activation comment still references cargo setup (removed in #7).

Changes

• Add fmt recipe and include it in ci
• Add --all-features flag to check, lint, and test recipes
• Add doc recipe with RUSTDOCFLAGS="-D warnings" and include it in ci
• Add standalone msrv recipe (cargo +1.85 check) — not in ci, requires a second toolchain
• Fix pre-commit hook activation comment: cargo setup → just setup

Acceptance criteria

• just ci output sequence matches the ci job in ci.yml
• just ci passes locally