refactor: restructure codebase as monorepo

[JuroOravec]

Currently django-components extends Django's template syntax with things like literal lists, dicts, etc. This is currently implemented in Pure python, and it's fairly slow (adds ~1s on the first load for large pages with ~500 components).

I have re-implemented the extended Django syntax as a Rust create.

With that, I want to restructure this repo as monorepo.

There's several reasons:

• When packaged and built separately, each Rust-based python package comes at about 100MB. So instead I want to have a single djc-core package that provides a single API. So that no matter how many Rust crates there are, the size still is only those 100MB.

• The Rust->Python binding is done by PyO3. When I was updating this repo to support Python 3.14 (see Support Python 3.14 #10), I had to update it from pyo3 v0.19 to pyo3 v0.27. There was a lot of breaking changes, and it took 1-2 hrs to update it.

  By having a monorepo, I won't have to go through this with every single Rust create. Instead, all creates will be updated and managed simultaneously.

Packages:

• HTML transformer (current package)
• Django template parser (planned)
• Jinja-like in-template Python expression (this is something that needs to be discussed yet)
• And I have a hunch that there might be need for a CSS transformer for applying custom selectors to CSS for implementing CSS scoping.

[JuroOravec]

This also means that the package that django-components will depend on will be renamed to djc-core. But the public API of djc-core remains the same.

[JuroOravec]

djc-core is the public API of this project. It's what will get exposed to Python. Inside it, it just re-exports other Rust crates.

[JuroOravec]

CC @EmilStenstrom

Also note that I have also renamed this repo from djc-core-html-parser to just djc-core