fix: backfill missing learnedData settings keys from old SavedVariables

EnsureLearnedData was using 'or' which never updates an existing table.
If learnedData was created by an older version of the code without
learnQuests/learnItems/learnObjects keys, those stayed nil (falsy),
causing every quest/item/object learn call to return immediately.

Now explicitly backfills each missing key to true so all categories
record correctly regardless of when the SavedVariables were first created.

Modules/QuestieLearner.lua

@@ -78,19 +78,35 @@ end
 
 local function EnsureLearnedData()
     if not Questie.db then return false end
-    Questie.db.global.learnedData = Questie.db.global.learnedData or {
-        npcs    = {},
-        quests  = {},
-        items   = {},
-        objects = {},
-        settings = {
-            enabled      = true,
-            learnNpcs    = true,
-            learnQuests  = true,
-            learnItems   = true,
-            learnObjects = true,
-        },
-    }
+    local ld = Questie.db.global.learnedData
+    if not ld then
+        Questie.db.global.learnedData = {
+            npcs    = {},
+            quests  = {},
+            items   = {},
+            objects = {},
+            settings = {
+                enabled      = true,
+                learnNpcs    = true,
+                learnQuests  = true,
+                learnItems   = true,
+                learnObjects = true,
+            },
+        }
+    else
+        -- Backfill sub-tables that may be missing from older SavedVariables
+        ld.npcs    = ld.npcs    or {}
+        ld.quests  = ld.quests  or {}
+        ld.items   = ld.items   or {}
+        ld.objects = ld.objects or {}
+        ld.settings = ld.settings or {}
+        local s = ld.settings
+        if s.enabled      == nil then s.enabled      = true end
+        if s.learnNpcs    == nil then s.learnNpcs    = true end
+        if s.learnQuests  == nil then s.learnQuests  = true end
+        if s.learnItems   == nil then s.learnItems   = true end
+        if s.learnObjects == nil then s.learnObjects = true end
+    end
     return true
 end