Suppress aura cache fallback when descriptor is authoritative

Stuck auras (pfUI issue #20 part 2): a no-duration debuff (Ghost/Spirit
in battlegrounds) stayed visible after the unit resurrected. It can only
come from the Aura::Source cache fallback — the descriptor path re-reads
the live aura array each call.

The aura is cached with expirationMs == 0 (infinite), so OnWorldTick
never expires it, and its real removal came via a bulk object drop
(death/leave-visibility, then resurrect) rather than a per-aura removal,
so OnAuraRemoved never fired to evict it. The infinite entry lingered and
the fallback resurrected it on the now-alive unit.

The fallback only exists for rogue stealth and party range fluctuation,
which both clear the unit's entire aura array at once. Gate both fallback
entry points on DescriptorHasVisibleAura: if the descriptor exposes any
live aura it's authoritative, so a cache-only aura is genuinely gone.
Stealth/range recovery is unaffected — those produce a wholesale-empty
aura array, so the fallback still fires there exactly as before.

Author: brues-code

src/aura/Data.cpp

@@ -492,6 +492,25 @@ void PushFromCache(void *L, const uint8_t *unit,
                c.casterGuid);
 }
 
+// True if `unit`'s descriptor currently exposes any visible aura in either
+// range. The cache fallback is only trustworthy when the descriptor has been
+// wholesale-cleared: the two states it exists for — rogue stealth and party
+// range fluctuation — clear the *entire* aura array at once. If the unit shows
+// even one live aura, the descriptor is authoritative, so a cache entry the
+// descriptor lacks is a genuinely-gone aura we never saw removed (e.g. a
+// no-duration debuff — Ghost/Spirit — on a unit that died and resurrected out
+// of our visibility, so no OnAuraRemoved fired and its infinite entry never
+// expired). Surfacing it then produces a stuck phantom.
+bool DescriptorHasVisibleAura(const uint8_t *unit) {
+    if (unit == nullptr)
+        return false;
+    for (int slot = 0; slot < Offsets::UNIT_AURA_TOTAL; ++slot) {
+        if (IsSlotPopulated(unit, slot))
+            return true;
+    }
+    return false;
+}
+
 // Counts populated descriptor slots matching `filter` (and `playerOnly`).
 int CountSlots(const uint8_t *unit, Filter filter, bool playerOnly) {
     if (unit == nullptr)
@@ -540,6 +559,8 @@ bool PushNthCacheFallback(void *L, const uint8_t *unit, int oneBasedIndex,
                           Filter filter, bool playerOnly) {
     if (unit == nullptr)
         return false;
+    if (DescriptorHasVisibleAura(unit))
+        return false; // descriptor authoritative — see DescriptorHasVisibleAura
     // The descriptor held `descCount` matches; the caller already found fewer
     // than `oneBasedIndex` there, so the cache supplies index
     // `oneBasedIndex - descCount` (1-based) of the entries it didn't.
@@ -568,6 +589,8 @@ void AppendCacheFallbacks(void *L, const uint8_t *unit, Filter filter,
                           bool playerOnly, int outerIdx, int &nextKey) {
     if (unit == nullptr)
         return;
+    if (DescriptorHasVisibleAura(unit))
+        return; // descriptor authoritative — see DescriptorHasVisibleAura
     const uint64_t guid = UnitGuid(unit);
     if (guid == 0)
         return;