chore: add #![forbid(unsafe_code)] to safe Rust crates

Adds the forbid(unsafe_code) crate-level attribute to all Rust crates
that do not use unsafe code, hardening the safety guarantee at compile
time.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: hyperpolymath

crates/hesinfo/src/main.rs

@@ -7,6 +7,7 @@
 //!   generate - Generate a BIND-format zone file
 //!   validate - Validate a zone file
 
+#![forbid(unsafe_code)]
 use std::path::PathBuf;
 
 use anyhow::{Context, Result};

crates/hesiod-lib/src/lib.rs

@@ -4,6 +4,7 @@
 //! Provides HS-class TXT record management, a lightweight UDP DNS server,
 //! and HTTP health/metrics endpoints for FlatRacoon network stack integration.
 
+#![forbid(unsafe_code)]
 pub mod config;
 pub mod health;
 pub mod records;