Add configurable project fixture loading mechanism

[nrjadkry]

Overview

This PR introduces a configuration-based approach for loading project-specific fixtures

Changes

• Add PROJECT_FIXTURES setting to define project fixture loading order
• Update tasks.py to automatically load project fixtures after core fixtures

Example Configuration

PROJECT_FIXTURES = [
    # List project-related fixture files here, in the order they should be loaded.
    'fixtures/menus.json',
    'fixtures/locales.json',
]