Clippy red on main: AtomicU32::fetch_update deprecated (cli/src/app_state.rs:58) under -D warnings

[hyperpolymath]

Clippy and Cargo check + clippy + fmt are red on main (seen at 2e424a6) and on every PR head.

Cause (job 112286781812, PR #903): cli/src/app_state.rs:58 calls AtomicU32::fetch_update, which the current stable toolchain deprecates (renamed to try_update). cargo clippy --workspace --locked -- -D warnings turns that into error: could not compile hypatia-cli (bin "hyper").

Acceptance criteria

• cli/src/app_state.rs builds without the deprecation warning on the CI toolchain (use try_update, or a version-gated alternative if the MSRV predates it).
• Clippy and Cargo check + clippy + fmt are green on main.

Deferred from #903 under AGENTS §5c item 3; #903 does not touch Rust.