refactor(seed): Refactor much of the codebase to setup seed

[david-bretaud-dev]

Goal

Still manage one codebase but be able to develop (and deploy here) the 2 websites (seed and all4trees).

The main benefit is that we don't have to recreate an application or manage duplicates.

What I wanted to do here:

• extract what is common or base (e.g. can be applied to any app)
• isolate what is purely related to one application

Normally, both apps are isolated and

• all 4 trees is hosted at /all4trees path
• seed is hosted at /seed path

The only thing that will problematic is

• different env variables (but can be defined at runtime differently for each app)
• the cookie for django session id

Highlight

• index.css is where we define the common theme. Tailwind directives are imported in each app css file, alongside the index.css => index.css is included in the stylesheet of either seed.css or all4trees.css
• I moved to each {app}.css file their own configuration of light and dark tokens (but the common token are still used in the shared index.css)
• Extracted i18n translations into: common, seed and all4trees namespaces
• Routing: there are some routes like "../${URLS.BLABLA}" with "relative" to "path" => the goal here is that, no matter the segment /seed or /all4trees, when i route from / to /login or to /dashboard, I want to do it relatively to the first segment
• Header => make it agnostic and rely on props injection

Path

1 index.html -> 1 main.tsx -> 1 global-router which creates the 2 segments, and each app is lazy loaded.

[severo]

sorry, but it's a lot for me to review, when I don't know the codebase yet. If it'(s OK, I prefer to let you review @arnaudfnr for this one