Establish project architecture and design decisions

src/mka/models/base.py

@@ -0,0 +1,25 @@
+"""Shared base classes for the Meeting Assistant domain model."""
+
+from datetime import datetime, timezone
+from uuid import UUID, uuid4
+
+from pydantic import BaseModel, ConfigDict, Field
+
+
+def utc_now() -> datetime:
+    """Return the current time as a timezone-aware UTC datetime."""
+    return datetime.now(timezone.utc)
+
+
+class DomainModel(BaseModel):
+    """Base class for persistent domain entities."""
+
+    model_config = ConfigDict(
+        extra="forbid",
+        validate_assignment=True,
+        use_enum_values=False,
+    )
+
+    id: UUID = Field(default_factory=uuid4)
+    created_at: datetime = Field(default_factory=utc_now)
+    updated_at: datetime = Field(default_factory=utc_now)