Improper singletons migration to clean Meyer's singletons (cherry-pick) (#2082)

# Pull Request

- Applies the clean and corrected singletons, Meyer pattern. (cherry
picked from @SmashingQuasar )

Testing by just playing the game in various ways. Been tested by myself
@Celandriel and @SmashingQuasar
---

## Complexity & Impact

- Does this change add new decision branches?
    - [x] No
    - [ ] Yes (**explain below**)

- Does this change increase per-bot or per-tick processing?
    - [x] No
    - [ ] Yes (**describe and justify impact**)

- Could this logic scale poorly under load?
    - [x] No
    - [ ] Yes (**explain why**)

---

## Defaults & Configuration

- Does this change modify default bot behavior?
    - [x] No
    - [ ] Yes (**explain why**)

---

## AI Assistance

- Was AI assistance (e.g. ChatGPT or similar tools) used while working
on this change?
    - [x] No
    - [ ] Yes (**explain below**)
---

## Final Checklist

- [x] Stability is not compromised
- [x] Performance impact is understood, tested, and acceptable
- [x] Added logic complexity is justified and explained
- [x] Documentation updated if needed

---

## Notes for Reviewers

Anything that significantly improves realism at the cost of stability or
performance should be carefully discussed
before merging.

---------

Co-authored-by: Nicolas Lebacq <nicolas.cordier@outlook.com>
Co-authored-by: Keleborn <22352763+Celandriel@users.noreply.github.com>

src/Ai/Base/Actions/GenericActions.cpp

@@ -113,7 +113,7 @@ bool TogglePetSpellAutoCastAction::Execute(Event event)
     }
 
     // Debug message if pet spells have been toggled and debug is enabled
-    if (toggled && sPlayerbotAIConfig->petChatCommandDebug == 1)
+    if (toggled && sPlayerbotAIConfig.petChatCommandDebug == 1)
         botAI->TellMaster("Pet autocast spells have been toggled.");
 
     return toggled;
@@ -185,7 +185,7 @@ bool SetPetStanceAction::Execute(Event /*event*/)
     }
 
     // Get the default pet stance from the configuration
-    int32 stance = sPlayerbotAIConfig->defaultPetStance;
+    int32 stance = sPlayerbotAIConfig.defaultPetStance;
     ReactStates react = REACT_DEFENSIVE;
     std::string stanceText = "defensive (from config, fallback)";
 
@@ -221,7 +221,7 @@ bool SetPetStanceAction::Execute(Event /*event*/)
     }
 
     // If debug is enabled in config, inform the master of the new stance
-    if (sPlayerbotAIConfig->petChatCommandDebug == 1)
+    if (sPlayerbotAIConfig.petChatCommandDebug == 1)
         botAI->TellMaster("Pet stance set to " + stanceText + " (applied to all pets/guardians).");
 
     return true;