refactor: use find_or_create_by with block (PR #2558)

Refactored per olleolleolle's suggestion:
- Use find_or_create_by(member, invitation) with block for status
- Check processed_at instead of persisted? for retry detection
- Cleaner, more idiomatic Rails pattern

Author: mroderick

app/services/invitation_logger.rb

@@ -23,7 +23,7 @@ def log_success(member, invitation = nil)
     return unless @log
 
     entry = find_or_build_entry(member, invitation, :success)
-    return entry if entry.persisted?
+    return entry if entry.processed_at
 
     entry.assign_attributes(processed_at: Time.current)
     save_entry(entry, :success_count)
@@ -33,7 +33,7 @@ def log_failure(member, invitation, error)
     return unless @log
 
     entry = find_or_build_entry(member, invitation, :failed)
-    return entry if entry.persisted?
+    return entry if entry.processed_at
 
     entry.assign_attributes(
       failure_reason: error.message,
@@ -46,7 +46,7 @@ def log_skipped(member, invitation, reason)
     return unless @log
 
     entry = find_or_build_entry(member, invitation, :skipped)
-    return entry if entry.persisted?
+    return entry if entry.processed_at
 
     entry.assign_attributes(
       failure_reason: reason,
@@ -78,14 +78,9 @@ def fail_batch(error)
   private
 
   def find_or_build_entry(member, invitation, status)
-    existing_entry = @log.entries.find_by(member: member, invitation: invitation)
-    return existing_entry if existing_entry
-
-    @log.entries.new(
-      member: member,
-      invitation: invitation,
-      status: status
-    )
+    @log.entries.find_or_create_by(member: member, invitation: invitation) do |entry|
+      entry.status = status
+    end
   end
 
   def save_entry(entry, counter)