trim_entries: take ContextBudget instead of recomputing

compact() already computes context_budget() — pass it to trim_entries
so it has access to all budget components without recomputing them.

Co-Authored-By: Proof of Concept <poc@bcachefs.org>

src/agent/mod.rs

@@ -987,11 +987,12 @@ impl Agent {
         self.load_startup_journal();
 
         // Dedup memory, trim to budget
+        let budget = self.context_budget();
         let entries = self.context.entries.clone();
         self.context.entries = crate::agent::context::trim_entries(
-            &self.context,
             &entries,
             &self.tokenizer,
+            &budget,
         );
 
         let after = self.context.entries.len();