fix(api): handle null/None values in API parsing

Added safe_decimal() helper to handle None/empty values from API
that were causing decimal.ConversionSyntax errors.

Fixed parsers:
- NexusHealingTool: Uses safe_decimal for decay/heal amounts
- NexusRing: Uses safe_decimal for max_tt/min_tt
- NexusClothing: Safely handles None buff values

Errors were occurring when API returned null for numeric fields
instead of 0.

core/nexus_full_api.py

@@ -3,7 +3,7 @@ Complete Entropia Nexus API Integration for Lemontropia Suite
 Fetches all gear types: weapons, armors, plates, attachments, enhancers, healing, rings, clothes, pets
 """
 
-from decimal import Decimal
+from decimal import Decimal, InvalidOperation
 from dataclasses import dataclass
 from typing import Optional, List, Dict, Any
 import requests
@@ -191,6 +191,16 @@ class NexusEnhancer(NexusItem):
         )
 
 
+def safe_decimal(value: Any, default: str = "0") -> Decimal:
+    """Safely convert a value to Decimal, handling None and invalid values."""
+    if value is None or value == "":
+        return Decimal(default)
+    try:
+        return Decimal(str(value))
+    except (InvalidOperation, ValueError, TypeError):
+        return Decimal(default)
+
+
 @dataclass
 class NexusHealingTool(NexusItem):
     """Healing tool from Entropia Nexus API."""
@@ -208,8 +218,8 @@ class NexusHealingTool(NexusItem):
         economy = props.get('Economy', {})
         heal = props.get('Heal', {})
         
-        decay = Decimal(str(economy.get('Decay', 0)))
-        heal_amount = Decimal(str(heal.get('Amount', 0)))
+        decay = safe_decimal(economy.get('Decay'))
+        heal_amount = safe_decimal(heal.get('Amount'))
         heal_per_pec = heal_amount / decay if decay > 0 else Decimal('0')
         
         return cls(
@@ -221,7 +231,7 @@ class NexusHealingTool(NexusItem):
             decay=decay,
             heal_per_pec=heal_per_pec,
             type=props.get('Type', 'fap'),
-            profession_level=int(props.get('RequiredLevel', 0)),
+            profession_level=int(props.get('RequiredLevel', 0) or 0),
             is_limited='(L)' in data.get('Name', ''),
         )
 
@@ -242,14 +252,14 @@ class NexusRing(NexusItem):
         props = data.get('Properties', {})
         economy = props.get('Economy', {})
         effects_data = props.get('Effects', {})
-        
+
         # Parse effects (usually under "Effects on Equip")
         effects = {}
         if 'Effects on Equip' in effects_data:
             effects = effects_data['Effects on Equip']
         elif isinstance(effects_data, dict):
             effects = effects_data
-            
+
         return cls(
             id=data.get('Id', 0),
             name=data.get('Name', 'Unknown'),
@@ -258,8 +268,8 @@ class NexusRing(NexusItem):
             slot=props.get('Slot', 'Left Finger'),
             gender=props.get('Gender', 'Both'),
             effects=effects,
-            max_tt=Decimal(str(economy.get('MaxTT', 0))),
-            min_tt=Decimal(str(economy.get('MinTT', 0))),
+            max_tt=safe_decimal(economy.get('MaxTT')),
+            min_tt=safe_decimal(economy.get('MinTT')),
             is_limited='(L)' in data.get('Name', ''),
         )
 
@@ -270,13 +280,19 @@ class NexusClothing(NexusItem):
     slot: str  # 'face', 'body', 'legs', 'feet'
     buffs: Dict[str, Decimal]
     is_cosmetic: bool
-    
+
     @classmethod
     def from_api(cls, data: Dict[str, Any]) -> "NexusClothing":
         """Create from API response."""
         props = data.get('Properties', {})
-        buffs = {k: Decimal(str(v)) for k, v in props.get('Buffs', {}).items()}
-        
+        buffs_raw = props.get('Buffs', {}) or {}
+        buffs = {}
+        for k, v in buffs_raw.items():
+            try:
+                buffs[k] = safe_decimal(v)
+            except:
+                buffs[k] = Decimal('0')
+
         return cls(
             id=data.get('Id', 0),
             name=data.get('Name', 'Unknown'),