pi-toolchain: v0.9.0

Minor Changes

• 11546d1: Add nix shell / devShell rewriting rule

Patch Changes

• f0406b1: Update Pi devDependencies to 0.79.9. Widen peerDependency ranges for @earendil-works/pi-coding-agent and @earendil-works/pi-tui from >=0.74.0 <1 to * to match the canonical Pi package convention in docs/packages.md. No runtime behavior changes; no post-0.74 APIs are used.