feat: Create a Demo Django website for quick demo / testing

[FlipperPA]

What

This structure creates a minimal Django website we can use as a demo and for testing new features.

Why

This pattern allows for quick testing with a browser during feature development.

How

Added a Django app. I'm sure there are ways we can improve the installation process in the README, but I started with raw SQL at the psql CLI. I kept the single view in the urls.py file, just for simplicity. We can iterate on this moving forward.

Tests

Passes the suite.

[CLAassistant]

All committers have signed the CLA.

[ankitml]

This is supercool. Having and end to end example in there make everything visual. Would you consider it okay to make it part of examples instead of making test an app? Although I wouldnt worry about existing examples since they are runnable code snippets and not a django app in themselves.. But something like this could be a good option

examples/
  README.md
  quickstart/
  ...
  demo_site/
    README.md
    manage.py
    demo_site/settings.py
    demo_site/urls.py
    search_demo/views.py
    search_demo/models.py
    search_demo/templates/search_demo/search.html

and then in examples/Readme.md the instructions can be something like

source scripts/run_paradedb.sh
cd examples/demo_site
uv run python manage.py migrate
uv run python manage.py runserver

what do you think?

[FlipperPA]

Sure, that might be better in the long run, @ankitml. It might also be better to have some full-text examples; we could pull a few chapters of a public domain book from Gutenberg or something like that. I was just trying to keep the amount of extra code to maintain to a minimum, but we can still keep it pretty lean.