Release v2.1.1

Fix rand 0.10 compile error (RngExt trait import) and ship version
bump alongside DELETE_ON_FAILURE, proportional jitter, and dependency
refresh changes already merged on master.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/main.rs

@@ -14,7 +14,7 @@ use crate::pp::PP;
 use std::collections::HashSet;
 use std::sync::atomic::{AtomicBool, Ordering};
 use std::sync::Arc;
-use rand::Rng;
+use rand::RngExt;
 use reqwest::Client;
 use tokio::signal;
 use tokio::time::{sleep, Duration};