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

tray/src-tauri/src/lib.rs

@@ -5,6 +5,7 @@
 //! their boj-server instance, control resource allocation, subscribe
 //! to cartridge catalogues, and monitor federation status.
 
+#![forbid(unsafe_code)]
 mod server;
 mod tray;