[metrics] charon-metrics/Cargo.toml missing lints.workspace = true — lint policy unenforced

[obchain]

Refs #50

File: crates/charon-metrics/Cargo.toml

Problem

charon-metrics has no [lints] section opting into workspace lints. Workspace policy (forbid unsafe_code, deny arithmetic_side_effects, cast_possible_truncation, unwrap_used) does not apply. Same recurring gap from PR #41 #165, PR #43 #189, PR #45 #211.

Fix

Add to crates/charon-metrics/Cargo.toml:

[lints]
workspace = true

Verify root Cargo.toml [workspace.lints] is populated (sibling issue from PR #45).

[obchain]

Fixed on feat/22-prometheus-metrics (9a9a938): workspace.lints populated + charon-metrics opts in.