cache: a byte budget of 256 bytes per entry bounds the cached answers, evicting by clock, and a full or failed copy is counted instead of swallowed

src/app.zig

@@ -718,7 +718,7 @@ fn serve(r: cli.Runner, args: cli.RunArgs) !u8 {
     const both = blk: {
         const c = try gpa.create(dns_cache.DnsCache);
         errdefer gpa.destroy(c);
-        c.* = try .init(gpa, cfg.cache);
+        c.* = try .init(gpa, .sized(cfg.cache.size));
         errdefer c.deinit();
 
         const l = try gpa.create(rate_limiter.RateLimiter);