Fail @focus clauses quietly when no focus is set

`[@focus,...] X` with no focus set printed "Invalid target" before falling
through to the next clause, which the new `[@mouseover][@focus][] X` idiom
turned into a message on every press. The noise came from a pre-ClassicAPI
name-based fallback in DoWithConditionals: with no native focus token,
TryTargetFocus resolved UnitName('focus') to nil and could never succeed,
so the branch only ever reached the error print. GetFocusUnitId's own
contract already says @focus should fall through silently.

Both evaluators now fail the clause quietly when GetFocusUnitId is nil,
the same way @mouseover does, so display and execution agree (TestAction
previously evaluated against "target" in that case). GetFocusName,
TryTargetFocus and pfUI's FocusNameHook were only reachable through that
path and are removed.

Compatibility/pfUI.lua

@@ -22,19 +22,6 @@ function Extension.DLOG(msg)
     end
 end
 
-function Extension.FocusNameHook()
-    local hook = Extension.internal.memberHooks[CleveRoids]["GetFocusName"]
-    local target = hook.original()
-
-    if pfUI and pfUI.uf and pfUI.uf.focus and pfUI.uf.focus.unitname then
-        target = pfUI.uf.focus.unitname
-    end
-
-    --Extension.DLOG(target)
-
-    return target
-end
-
 -- Check if pfUI's macrotweak module is loaded
 function Extension.IsPfUIMacrotweakLoaded()
     if not pfUI then return false end
@@ -614,7 +601,6 @@ end
 
 function Extension.OnLoad()
     Extension.DLOG("Extension pfUI Loaded.")
-    Extension.HookMethod(CleveRoids, "GetFocusName", "FocusNameHook", true)
 
     -- Export extension for external access
     CleveRoids.Compatibility_pfUI = Extension