Rename push to process on PushTarget for clearer semantics

"Push to target" reads naturally - we push the notification to the
target. "Target processes" also makes sense - the target receives
and handles the notification in its own way.

- Add class method PushTarget.process(notification) that instantiates
  and calls the instance method
- Rename instance method from push to process
- Add private push_to helper in Pushable for readable iteration

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

app/models/notification/push_target.rb

@@ -3,11 +3,15 @@ class Notification::PushTarget
 
   delegate :card, to: :notification
 
+  def self.process(notification)
+    new(notification).process
+  end
+
   def initialize(notification)
     @notification = notification
   end
 
-  def push
+  def process
     return unless should_push?
 
     perform_push

app/models/notification/pushable.rb

@@ -16,9 +16,10 @@ module Notification::Pushable
 
     private
       def resolve_push_target(target)
-        if target.is_a?(Notification::PushTarget) then target
-        else
+        if target.is_a?(Symbol)
           "Notification::PushTarget::#{target.to_s.classify}".constantize
+        else
+          target
         end
       end
   end
@@ -28,9 +29,7 @@ module Notification::Pushable
   end
 
   def push
-    self.class.push_targets.each do |target|
-      target.new(self).push
-    end
+    self.class.push_targets.each { |target| push_to(target) }
   end
 
   def pushable?
@@ -42,6 +41,10 @@ module Notification::Pushable
   end
 
   private
+    def push_to(target)
+      target.process(self)
+    end
+
     def payload_type
       source_type.presence_in(%w[ Event Mention ]) || "Default"
     end