fix(CORE-001D3B): validate alert history entry types

app/models/alerts.py

@@ -3,6 +3,7 @@
 from __future__ import annotations
 
 import json
+import math
 from dataclasses import asdict, dataclass
 from pathlib import Path
 from typing import Any
@@ -25,6 +26,22 @@ class AlertEvent:
     updated_at: str
     email_alerts_enabled: bool
 
+    def __post_init__(self) -> None:
+        for field_name in ("severity", "message", "updated_at"):
+            value = getattr(self, field_name)
+            if not isinstance(value, str):
+                raise TypeError(f"{field_name} must be a string")
+        for field_name in ("ltv_ratio", "warning_threshold", "critical_threshold", "spot_price"):
+            value = getattr(self, field_name)
+            if isinstance(value, bool) or not isinstance(value, (int, float)):
+                raise TypeError(f"{field_name} must be numeric")
+            numeric_value = float(value)
+            if not math.isfinite(numeric_value):
+                raise ValueError(f"{field_name} must be finite")
+            setattr(self, field_name, numeric_value)
+        if not isinstance(self.email_alerts_enabled, bool):
+            raise TypeError("email_alerts_enabled must be a bool")
+
     def to_dict(self) -> dict[str, Any]:
         return asdict(self)