Models: Update to match SQL

refs #7303

Conflicts:
	src/dashboard/src/main/models.py
Models: Update MCP models to match SQL

refs #7303

Conflicts:
	src/dashboard/src/main/models.py
File, Task: dates are nullable, default to NULL

Previously, since no default value was specified, the default value
was "0000-00-00", a value that is impossible to filter on in Django.
databaseFunctions: use Django models

refs #7137
fileOperations: use Django models

refs #7137
elasticSearchFunctions: use Django models

refs #7137
storageService: use Django models

refs #7137
MCPClient: use Django models

refs #7137