feat: validate and store the size choice in redmine_tonalmine (T6)

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

redmine_tonalmine/lib/redmine_tonalmine/appearance.rb

@@ -1,12 +1,13 @@
 module RedmineTonalmine
-  # Validates appearance hashes ({mode, contrast, palette, seed, css}) coming from users and from
+  # Validates appearance hashes ({mode, contrast, size, palette, seed, css}) coming from users and from
   # the Display settings form. Any part may be missing: it then falls back to the default.
   module Appearance
     MODES = %w[auto light dark].freeze
     CONTRASTS = %w[standard medium high].freeze
+    SIZES = %w[compact normal large].freeze
     # Ids must match PALETTES in tonalmine/javascripts/theme.js (tools/palettes checks this).
     PALETTES = %w[purple blue green orange].freeze
-    KEYS = %w[mode contrast palette seed css].freeze
+    KEYS = %w[mode contrast size palette seed css].freeze
     MAX_CSS = 32.kilobytes
 
     module_function
@@ -21,6 +22,7 @@ module RedmineTonalmine
       end
       errors << 'invalid mode' if prefs['mode'] && !MODES.include?(prefs['mode'])
       errors << 'invalid contrast' if prefs['contrast'] && !CONTRASTS.include?(prefs['contrast'])
+      errors << 'invalid size' if prefs['size'] && !SIZES.include?(prefs['size'])
       errors.concat(custom_errors(prefs))
       errors
     end
@@ -30,6 +32,7 @@ module RedmineTonalmine
       prefs = normalize(hash)
       prefs.delete('mode') unless MODES.include?(prefs['mode'])
       prefs.delete('contrast') unless CONTRASTS.include?(prefs['contrast'])
+      prefs.delete('size') unless SIZES.include?(prefs['size'])
       prefs = prefs.except('palette', 'seed', 'css') if custom_errors(prefs).any?
       prefs.compact
     end