Fix: Internationalize hardcoded UI strings (Issue #1787)

- Replace hardcoded 'Inventory Items', 'Character Items', 'Other' with i18n keys
- Internationalize 'New Effect' default name in active effects
- Fix hardcoded 'Roll Formula' and 'Formula Roll' labels in roll tables
- Add translation keys to lang/en.json for proper localization support
- Ensures all UI strings can be translated to other languages

Fixes #1787: I18n: Some UI strings still seem to be hardcoded

lang/en.json

@@ -39,6 +39,11 @@
 
     "DAGGERHEART": {
         "CharacterSheet": "Character Sheet",
+        "ITEM_GROUPS": {
+            "INVENTORY": "Inventory Items",
+            "CHARACTER": "Character Items",
+            "OTHER": "Other"
+        },
         "ACTIONS": {
             "TYPES": {
                 "attack": {
@@ -1942,6 +1947,9 @@
                 }
             }
         },
+        "ACTIVE_EFFECT": {
+            "NEW_EFFECT": "New Effect"
+        },
         "EFFECTS": {
             "ApplyLocations": {
                 "attackRoll": {
@@ -2623,8 +2631,10 @@
             }
         },
         "ROLLTABLES": {
+            "DEFAULT_FORMULA_NAME": "Roll Formula",
             "FIELDS": {
-                "formulaName": { "label": "Formula Name" }
+                "formulaName": { "label": "Formula Name" },
+                "formula": { "label": "Formula Roll" }
             },
             "formula": "Formula"
         },