feat: ✨ add builtin log function

lib/comfpile/artefact.rb

@@ -61,6 +61,8 @@ module Comfpile
             @included_artefacts = []
             @referenced_artefacts = []
 
+            @log_current_level = :debug
+            @log_current_line  = "Not started..."
 
             @steps = []
             @step_additions = nil
@@ -86,6 +88,30 @@ module Comfpile
             @parameters[key] = value
         end
 
+        #
+        # Log an event for this artefact.
+        # Saves the given argument as log line,
+        # optionally prints it to a logger. Use this to 
+        # save state progress messages as well as
+        # error messages.
+        #
+        # @param [String] text Text message to log
+        # @param [Symbol] state Level to log at. Known levels
+        #  are:
+        #  - :debug
+        #  - :info
+        #  - :warning
+        #  - :error
+        #
+        def log(text, level = :debug)
+            @log_current_line = text
+            @log_current_level = level
+
+            puts "> #{@state} #{@target}: #{text}"
+
+            nil
+        end
+
         private def add_step_data(data)
             @step_additions ||= []