Description

This PR fixes the Makefile to ensure the local development environment is correctly initialized. It fixes a major issue where the catalog tree and courses were not being loaded into the database.

Closes #263
Closes #366

Key Changes

1. Catalog Tree Initialization

• Added the mandatory creation of the root "ULB" category during database setup.
• Added the load_tree and load_courses commands. The previous Makefile missed these steps, leaving the local catalog empty after initialization.

2. Improved Data Creation logic

• Users: Updated user creation to use get_or_create with defaults to prevent errors if the user already exists. It also correctly sets is_moderator=True for the primary user.
• Tags: Simplified the tag creation logic to be cleaner and more readable.

3. Environment & Syntax

• Switched the Python runner to PY=uv run for compatibility with the current project setup.
• Added .PHONY to prevent conflicts with local files named init or database.

Manual Testing

1. Ran make database from a fresh state.
2. Verified that:
   • The "ULB" root category is created.
   • All courses and the category tree are correctly loaded via load_tree and load_courses.
   • Test users and tags are created without errors.
   • Fake documents are generated and linked to the new courses.