refactor: key fake-player tracking by ObjectGuid instead of raw Player*

[Nyeriah]

Summary

Switches the fake-player tracking from unordered_map<Player*, FakePlayer> _fakePlayerStore to unordered_set<ObjectGuid> _fakePlayerGuids, drops the FakePlayer struct + GetFakePlayer() method, and adds a GUID-form ClearFakePlayer(ObjectGuid) that resolves the player via ObjectAccessor::FindPlayer and handles online + offline cleanup uniformly.

Why GUID

Raw Player* keys can outlive the player they describe. The OnPlayerLogout hook intentionally skips ClearFakePlayer while a WG war is active (so a relog can rejoin without re-faking), but the Player object is still deleted at the end of the logout flow. The entry in _fakePlayerStore survives with a dangling pointer key, and the next new Player(...) allocation can reuse that address — _fakePlayerStore.contains(newPlayer) then returns true for an unrelated character, and ClearFakePlayer would stamp the new player with the old player's stored race/morph/team/faction.

ObjectGuid is the project-wide convention for any reference that may outlive a single call/tick (see the project CLAUDE.md "Long-lived references" note); this module's Player*-keyed map was the lone exception.

Why no struct

Six of the seven FakePlayer fields are derivable on demand:

• RealRace ← getRace(true) (m_realRace survives setRace, which only modifies m_race per Unit::setRace).
• RealTeamID ← GetTeamId(true) (derived from m_realRace).
• RealNativeMorph ← ChrRacesEntry::model_m/model_f for the player's gender — by definition the native model for race+gender.
• Fake{Race,Morph,TeamID} were write-once values already on the live player after fake application; only the dead-code ApplyFakeVisualsForBF (removed in refactor(WG): remove unused PrepareFakeTeamForBF/ApplyFakeVisualsForBF #155) and the debug dump ever read them back.

Only RealMorph (the DisplayId snapshot at fake time) is genuinely non-derivable; it captured the player's active transformation visual (bear form, ghost wolf, transform aura). That snapshot was fragile though — the aura it intended to preserve may have expired during the fake — so the new code derives the canonical race+gender model on clear; an active transformation aura will reapply on its next tick.

Side effects

• OnBattlefieldWarEnd correctly drops offline entries now. Previously the loop did FindPlayer(guid) and silently skipped offline GUIDs, leaking their entries into _fakePlayerStore forever. The new GUID-form ClearFakePlayer erases the set entry whether the player is online or not.
• Loop collapses to one line per GUID — no per-player nullptr/IsPlayerFake checks needed; the GUID form is a no-op for unfaked entries.
• .cfbg debug no longer prints a "Fake record:" block. The block was strictly redundant with the live "Native" / "Current" lines above it (which print real race/team from getRace(true) / GetTeamId(true) and current race/team/display from the live player fields). SQL help text updated accordingly.

Test plan

• Build module under AzerothCore (-DMODULES=static) — confirm no unresolved symbols.
• Cross-faction BG entry → fake morph applies; BG end → race/team/display restored to native.
• Cross-faction WG entry → fake morph applies on war accept; war end → race/team/display restored for all war participants (including any who logged out mid-war once they relog).
• Logout in WG during war → relog post-war → character loads native race/faction from DB (already covered by the existing save path, since SaveToDB writes getRace(true) = m_realRace, not the fake m_race).
• .cfbg debug still prints sensible state for both faked and unfaked targets.