Add equipment loan feature and USB bulk control

- Add emprestimos (equipment loan) module in Convex with queries/mutations
- Create emprestimos page with full CRUD and status tracking
- Add USB bulk control to admin devices overview
- Fix Portuguese accents in USB policy control component
- Fix dead code warnings in Rust agent
- Fix tiptap type error in rich text editor

apps/desktop/src-tauri/src/agent.rs

@@ -1134,6 +1134,7 @@ async fn post_heartbeat(
 struct UsbPolicyResponse {
     pending: bool,
     policy: Option<String>,
+    #[allow(dead_code)]
     applied_at: Option<i64>,
 }