Add exclude transaction rule action (#437)

* Initial plan

* Add ExcludeTransaction rule action executor with tests

Co-authored-by: jjmata <187772+jjmata@users.noreply.github.com>

* Copy clarification

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: jjmata <187772+jjmata@users.noreply.github.com>
Co-authored-by: Juan José Mata <juanjo.mata@gmail.com>

app/models/rule/action_executor/exclude_transaction.rb

@@ -0,0 +1,26 @@
+class Rule::ActionExecutor::ExcludeTransaction < Rule::ActionExecutor
+  def label
+    "Exclude from budgeting and reports"
+  end
+
+  def execute(transaction_scope, value: nil, ignore_attribute_locks: false, rule_run: nil)
+    scope = transaction_scope.with_entry
+
+    unless ignore_attribute_locks
+      # Filter by entry's locked_attributes, not transaction's
+      # Since excluded is on Entry, not Transaction, we need to check entries.locked_attributes
+      scope = scope.where.not(
+        Arel.sql("entries.locked_attributes ? 'excluded'")
+      )
+    end
+
+    count_modified_resources(scope) do |txn|
+      # enrich_attribute returns true if the entry was actually modified, false otherwise
+      txn.entry.enrich_attribute(
+        :excluded,
+        true,
+        source: "rule"
+      )
+    end
+  end
+end