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/mozo/counter.rb

@@ -23,5 +23,57 @@ module Mozo
       options[:initial] ||= 0
       connection.decr(key, options) rescue 0
     end
+
+    # Provision Redis counters from CouchDB aggregated data.
+    # Reads the Order.by_supplier_id_and_state view (reduce, grouped),
+    # and sets the corresponding Redis keys.
+    #
+    # Invoke via: rails runner 'Mozo::Counter.provision!'
+    #
+    def self.provision!
+      require 'couchrest'
+
+      db = Order.database
+      design = '_design/order_counter'
+      view   = 'by_supplier_id_and_state'
+
+      # Ensure the design doc exists
+      unless db.get(design) rescue nil
+        puts "[Counter.provision!] Creating design doc #{design}"
+        doc = YAML.safe_load(
+          File.read(Rails.root.join('drb_counter/couchdb_design.yml')),
+          permitted_classes: [Symbol]
+        )
+        doc['_id'] = design
+        doc['language'] ||= 'javascript'
+        db.save_doc(doc)
+      end
+
+      # Query with reduce + group to get per-supplier/per-state counts
+      result = db.view("#{design}/_view/#{view}", reduce: true, group: true, group_level: 2)
+      rows = result['rows'] || []
+
+      puts "[Counter.provision!] #{rows.size} counter keys to set"
+
+      rows.each do |row|
+        supplier_id, state = row['key']
+        count = row['value']
+
+        case state
+        when 'placed'
+          key = "supplier_counter:#{supplier_id}:orders_placed"
+        when 'active'
+          key = "supplier_counter:#{supplier_id}:orders_in_process"
+        else
+          next
+        end
+
+        set(key, count)
+        puts "  #{key} = #{count}"
+      end
+
+      puts "[Counter.provision!] Done."
+      rows.size
+    end
   end
 end