Add configurable limits for memory, map, and disk in IiifPrint

- Added `memory_limit`, `map_limit`, and `disk_limit` options to IiifPrint::Configuration with attr_accessors
- Updated iiif_print initializer to allow optional configuration of these limits
- Added example comments in configuration.rb for setting limits
- Ensures ImageMagick falls back to imagemagic-6-policy.xml limits if values are left unset

This change provides flexibility for resource management in image processing while retaining default behaviors.

lib/iiif_print/configuration.rb

@@ -4,6 +4,12 @@ class Configuration
     attr_writer :after_create_fileset_handler
 
     attr_writer :ingest_queue_name
+
+    # Example settings in the initializer:
+    # config.memory_limit = "512MiB"  # Limit for memory usage
+    # config.map_limit = "1GiB"       # Limit for map usage
+    # config.disk_limit = "20KP"      # Limit for disk usage
+    attr_accessor :memory_limit, :map_limit, :disk_limit
     ##
     # @return [Symbol, Proc]
     def ingest_queue_name

lib/iiif_print/image_tool.rb

@@ -74,12 +74,12 @@ def im_identify_geometry(lines)
 
     # @return [Array<String>] lines of output from imagemagick `identify`
     def im_identify
-      memory_limit = ENV["IM_MEMORY_LIMIT"]
-      map_limit = ENV["IM_MAP_LIMIT"]
-      disk_limit = ENV["IM_DISK_LIMIT"]
+      memory_limit = IiifPrint.config.memory_limit
+      map_limit = IiifPrint.config.map_limit
+      disk_limit = IiifPrint.config.disk_limit
 
       cmd = "identify"
-
+      
       cmd += " -limit memory #{memory_limit}" if memory_limit.present?
       cmd += " -limit map #{map_limit}" if map_limit.present?
       cmd += " -limit disk #{disk_limit}" if disk_limit.present?