fix(tracker): name and group quests built from partial records

Quests assembled from a Learner entry or a questDataOverrides entry that
never captured every field reach the tracker with nil fields, since GetQuest
copies rawdata key by key. Two of those show: a nil name printed as the
quest id, and a nil zoneOrSort that sent _GetZoneName down its very first
line, `if not zoneOrSort then return "Unknown Zone" end`, before it could
consult the quest log header the earlier fix added. Those objects are cached
for the session, so neither repaired itself.

GetQuest now fills a missing name from the quest log and defaults zoneOrSort
to 0, the value every caller already reads as "no zone on file" -- and which
some of them require, `quest.zoneOrSort > 0` erroring outright on nil.
_GetZoneName treats nil the same way rather than short-circuiting, which
also stops a nil quest from labelling its group Unknown Zone under the sort
modes that do not group by zone at all.

The tracker asks the quest log for a title before printing an id, so quests
already cached without a name come out right too, and the live-fallback
builder stops discarding the override data it just looked up.

Modules/Tracker/TrackerUtils.lua

@@ -809,7 +809,13 @@ local function _GetZoneName(zoneOrSort, questId, zoneNameOverride)
     if zoneNameOverride and zoneNameOverride ~= "" then
         return zoneNameOverride
     end
-    if not zoneOrSort then return "Unknown Zone" end
+
+    -- A quest assembled from a partial record -- a Learner entry that never captured the field,
+    -- an override carrying a single key -- reaches here with no zoneOrSort at all. That is the
+    -- same "nothing to look up" case as 0, and the quest log below still knows where the client
+    -- files the quest, so it must not short-circuit to Unknown Zone ahead of that.
+    zoneOrSort = zoneOrSort or 0
+
     local zoneName
     local sortObj = Questie.db.profile.trackerSortObjectives
     if sortObj == "byZone" or sortObj == "byZoneComplete" or sortObj == "byZoneCompleteReversed" or sortObj == "byZonePlayerProximity" or sortObj == "byZonePlayerProximityReversed" then
@@ -865,6 +871,22 @@ local function _GetZoneName(zoneOrSort, questId, zoneNameOverride)
     return zoneName
 end
 
+-- The client's own title for a quest, or nil if the player does not have it. Quest objects can
+-- reach the tracker without a usable name -- a questDataOverrides entry that carries no name
+-- field, a QuestLogCache row read before the client had filled the title in -- and since those
+-- objects are cached for the session, the name never repairs itself. The log always knows.
+function TrackerUtils:GetQuestLogTitleById(questId)
+    local questLogIndex = GetQuestLogIndexForQuest(questId)
+    if not questLogIndex then return nil end
+
+    local title = GetQuestLogTitle(questLogIndex)
+    if title and title ~= "" then
+        return title
+    end
+
+    return nil
+end
+
 -- IsComplete must be a method (called as quest:IsComplete()), and it reads the state the last
 -- refresh stored rather than closing over the state at build time -- these quests outlive many
 -- redraws, and a captured value would still claim the quest is unfinished after it is turned in.