Implement BaseModel class, TimestampMixin, TzDateTime type; cleanup Task model

tofu_api/app.py

@@ -6,6 +6,7 @@ from flask import Flask
 
 from tofu_api.api import TofuApiBlueprint
 from tofu_api.common.config import Config
+from tofu_api.common.json import JSONEncoder
 from tofu_api.dependencies import Dependencies
 
 # Enable deprecation warnings in dev environment
@@ -19,6 +20,7 @@ class App(Flask):
     """
     # Override Flask classes
     config_class = Config
+    json_encoder = JSONEncoder
 
     # Set type hint for config
     config: Config
@@ -57,7 +59,7 @@ class App(Flask):
         db = self.dependencies.get_sqlalchemy()
         db.init_database(self)
 
-        # Import models to fill the metadata object
+        # Import models to populate the database metadata
         import tofu_api.models  # noqa (unused import)