perf: tighten recall relevance threshold

Require >1 stem match so single-word noise queries don't surface
weakly-related memories.

src/lib/agentMemory.ts

@@ -158,7 +158,7 @@ export const agentMemory = {
       return { m, score: score + tagScore };
     });
     return scored
-      .filter((x) => x.score > 0)
+      .filter((x) => x.score > 1)
       .sort((a, b) => b.score - a.score || (b.m.created_at || "").localeCompare(a.m.created_at || ""))
       .slice(0, limit)
       .map((x) => x.m);