feat(counter): add Mozo::Counter.provision! to seed Redis from CouchDB

- Reads Order.by_supplier_id_and_state view (reduce, grouped)
- Sets Redis keys: supplier_counter:<id>:orders_placed / orders_in_process
- Creates design doc if missing (from drb_counter/couchdb_design.yml)
- Rake task: rails counters:provision
- Also invokable directly: rails runner 'Mozo::Counter.provision!'

lib/tasks/counters.rake

@@ -2,4 +2,9 @@ namespace :counters do
   task reset: :environment do
     Supplier.reset_counters!
   end
+
+  desc 'Provision Redis counters from CouchDB aggregated data'
+  task provision: :environment do
+    Mozo::Counter.provision!
+  end
 end