Slot 1 X opens gem picker instead of removing main skill

Guard the GemSelectControl focusLost+no-match branch (introduced by
upstream PR #1843) against deleting the main active skill, matching
the X-button handler's slot-1 protection.

Without this guard, clicking X on slot 1 would open the gem picker as
intended, but closing the picker (Escape / click-away / re-click X)
without selecting a gem would trigger
GemSelectControl:OnFocusLost -> UpdateGem(..., focusLost=true) ->
the new "elseif focusLost and not bufMatchesGem" branch in the
nameSpec callback, which calls deleteGem() and removes the main
active skill.

For slot >= 2 the upstream auto-clean behavior is preserved.

Author: marckaraujo

src/Classes/SkillsTab.lua

@@ -772,6 +772,10 @@ function SkillsTabClass:CreateGemSlot(index)
 			slot.enableGlobal2.state = true
 			slot.count:SetText(gemInstance.count)
 		elseif focusLost and not bufMatchesGem then
+			if index == 1 then
+				-- Slot 1 (main active skill) must never auto-delete on focus loss
+				return
+			end
 			return deleteGem()
 		elseif gemId == gemInstance.gemId then
 			if addUndo then