fix: cache form signature only after bar refresh actually runs

UPDATE_SHAPESHIFT_FORMS firing before the ActionBars module exists
cached the signature without refreshing, causing the identical later
event to be skipped.

Bartender4/CoAAuraConditionals.lua

@@ -129,11 +129,13 @@ refresh:SetScript("OnEvent", function(self, event)
     -- UPDATE_SHAPESHIFT_FORMS spam.
     local sig = currentFormSignature()
     if sig == lastFormSignature then return end
-    lastFormSignature = sig
 
     local mod = Bartender4 and Bartender4.GetModule and Bartender4:GetModule("ActionBars", true)
     if not mod or not mod.actionbars then return end
     for _, bar in pairs(mod.actionbars) do
         if bar and bar.UpdateStates then bar:UpdateStates() end
     end
+    -- Only cache the signature once a refresh actually ran, so an event
+    -- arriving before module init doesn't swallow the next identical one.
+    lastFormSignature = sig
 end)