gems: include vendored metrisk without hitime dependency

hitime is only needed for Metriks::Timer and requires native extensions.
Those do not compile with default settings under Ubuntu 26.04 or Alpine 3.24.

lib/metriks.rb

@@ -0,0 +1,27 @@
+# Vendored from metriks 0.9.9.8 — https://github.com/eric/metriks
+# Copyright (c) 2012 Eric Lindvall, MIT licensed.
+# Trimmed to the subset dyndnsd uses (meters + registry + reporters);
+# counter/gauge/timer/utilization_timer/histogram support was removed,
+# and the 'atomic'/'avl_tree'/'hitimes' dependencies were replaced or dropped.
+
+module Metriks
+  VERSION = '0.9.9.8'
+
+  def self.get(name)
+    Registry.default.get(name)
+  end
+
+  def self.meter(name)
+    Registry.default.meter(name)
+  end
+
+  def self.registry
+    Registry.default
+  end
+end
+
+require 'metriks/atomic'
+require 'metriks/ewma'
+require 'metriks/meter'
+require 'metriks/registry'
+require 'metriks/reporter/proc_title'