CC-2075: Update Rust to 1.92

[andy1li]

CC-2075: Update Rust to 1.92

---

Note

Updates Rust toolchain to 1.92 across starter, solution, and build configs.

• Switches buildpack to rust-1.92 in compiled_starters/rust/codecrafters.yml and solutions/.../codecrafters.yml
• Adds dockerfiles/rust-1.92.Dockerfile for building with Rust 1.92
• Updates README instructions to require cargo (1.92)
• Bumps required_executable to cargo (1.92) in starter_templates/rust/config.yml

^{Written by Cursor Bugbot for commit 371bf11. This will update automatically on new commits. Configure here.}

[linear]

CC-2075 Update to Gleam version 1.13.0