Player unit frame - cast bar appears when coming out of an instance despite being off

[Philboisvert]

[Lyrex]

This has been fixed. The Blizzard default castbar is now permanently suppressed via:

• PlayerCastingBarFrame:UnregisterAllEvents() + Hide() on startup
• A hooksecurefunc on Show that immediately re-hides it
• A PLAYER_ENTERING_WORLD handler that re-suppresses after zone changes (which is exactly the scenario that triggered this bug — Blizzard re-registers events on that frame during zone transitions)