feat: ✨ add mtime calculation for dependency analysis

lib/comfpile/engines/parser_engine.rb

@@ -129,6 +129,7 @@ module Comfpile
 
     class DependencyAnalysisArtefact < Artefact
         attr_reader :dependencies
+        attr_reader :mtime
 
         def initialize(*args, traverse: nil, **opts)
             super(*args, **opts)
@@ -143,11 +144,15 @@ module Comfpile
             @traverse = traverse || ['include', 'require', 'reference']
 
             add_step do
-                recursive_dependency_wait_step
+                iterative_dependency_wait_step
+            end
+
+            add_step do
+                @mtime = @dependencies.map(&:mtime).max
             end
         end
 
-        def recursive_dependency_wait_step
+        def iterative_dependency_wait_step
             dependency_unfurl = @dependency_waiting_on
             @dependency_waiting_on = []