fix: add values_callable to SQLAlchemy Enum columns

Add _enum_values helper and values_callable parameter to Enum columns
in message models to ensure proper enum value extraction for database
operations.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

models/database/message.py

@@ -48,6 +48,11 @@ class ParticipantType(str, enum.Enum):
     CUSTOMER = "customer"  # Customer model
 
 
+def _enum_values(enum_class):
+    """Extract enum values for SQLAlchemy Enum column."""
+    return [e.value for e in enum_class]
+
+
 class Conversation(Base, TimestampMixin):
     """
     Represents a threaded conversation between participants.
@@ -62,7 +67,7 @@ class Conversation(Base, TimestampMixin):
 
     # Conversation type determines participant structure
     conversation_type = Column(
-        Enum(ConversationType),
+        Enum(ConversationType, values_callable=_enum_values),
         nullable=False,
         index=True,
     )
@@ -82,7 +87,7 @@ class Conversation(Base, TimestampMixin):
     # Status flags
     is_closed = Column(Boolean, default=False, nullable=False)
     closed_at = Column(DateTime, nullable=True)
-    closed_by_type = Column(Enum(ParticipantType), nullable=True)
+    closed_by_type = Column(Enum(ParticipantType, values_callable=_enum_values), nullable=True)
     closed_by_id = Column(Integer, nullable=True)
 
     # Last activity tracking for sorting
@@ -135,7 +140,7 @@ class ConversationParticipant(Base, TimestampMixin):
     )
 
     # Polymorphic participant reference
-    participant_type = Column(Enum(ParticipantType), nullable=False)
+    participant_type = Column(Enum(ParticipantType, values_callable=_enum_values), nullable=False)
     participant_id = Column(Integer, nullable=False, index=True)
 
     # For vendor participants, track which vendor they represent
@@ -196,7 +201,7 @@ class Message(Base, TimestampMixin):
     )
 
     # Polymorphic sender reference
-    sender_type = Column(Enum(ParticipantType), nullable=False)
+    sender_type = Column(Enum(ParticipantType, values_callable=_enum_values), nullable=False)
     sender_id = Column(Integer, nullable=False, index=True)
 
     # Message content
@@ -208,7 +213,7 @@ class Message(Base, TimestampMixin):
     # Soft delete for moderation
     is_deleted = Column(Boolean, default=False, nullable=False)
     deleted_at = Column(DateTime, nullable=True)
-    deleted_by_type = Column(Enum(ParticipantType), nullable=True)
+    deleted_by_type = Column(Enum(ParticipantType, values_callable=_enum_values), nullable=True)
     deleted_by_id = Column(Integer, nullable=True)
 
     # Relationships