Fix Rust formatting failure in hg_analytics CI

[mdheller]

PR #5 now includes the upstream convergence spec and an initial formatting pass for crates/hg_analytics/src/lib.rs, but HellGraph CI still fails at cargo fmt --all --check.

Observed workflow state:

• docs-integrity job passes
• rust job fails at Format check
• clippy and tests are skipped because formatting fails first

Acceptance criteria:

• cargo fmt --all --check passes.
• cargo clippy --workspace --all-targets -- -D warnings runs.
• cargo test --workspace runs.
• PR Add upstream state and convergence specification #5 can merge without weakening the Rust formatting gate.