fix(rustproxy): prune stale per-route metrics, add per-route rate limiter caching and regex cache, and improve connection tracking cleanup to prevent memory growth

rust/crates/rustproxy/src/lib.rs

@@ -27,7 +27,7 @@
 pub mod challenge_server;
 pub mod management;
 
-use std::collections::HashMap;
+use std::collections::{HashMap, HashSet};
 use std::sync::Arc;
 use std::time::Instant;
 
@@ -565,6 +565,12 @@ impl RustProxy {
             vec![]
         };
 
+        // Prune per-route metrics for route IDs that no longer exist
+        let active_route_ids: HashSet<String> = routes.iter()
+            .filter_map(|r| r.id.clone())
+            .collect();
+        self.metrics.retain_routes(&active_route_ids);
+
         // Atomically swap the route table
         let new_manager = Arc::new(new_manager);
         self.route_table.store(Arc::clone(&new_manager));