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

overlay-daemon/src/main.rs

@@ -4,6 +4,7 @@
 //! Monitors rclone mount status and provides sync state to file managers
 //! via D-Bus and GIO emblems.
 
+#![forbid(unsafe_code)]
 use serde::{Deserialize, Serialize};
 use std::collections::HashMap;
 use std::path::PathBuf;

tray-daemon/src/main.rs

@@ -3,6 +3,7 @@
 //!
 //! Displays sync status in system tray with menu for common actions.
 
+#![forbid(unsafe_code)]
 use muda::{Menu, MenuEvent, MenuItem, PredefinedMenuItem, Submenu};
 use notify_rust::Notification;
 use serde::Deserialize;