docs: port to VitePress

Things that happen in this shameless squash:
- Removed 404 page
  - It doesn't work in VitePress and making it work in VitePress needs
    some invasive hack in the theme that I'm not willing to do
  - The default is more than enough, though
- Moved consoleVersionSelect include to another directory
  - This avoids being uploaded to Crowdin for translation
- Inline all SafeB9SInstaller includes
  - Not only do parameterized includes not work, but if/else statements
    don't work at all
- The sysupdate include parameter hasn't been used since MSET9, so it
  actually works just fine without any parameters. Hooray(?)
- Move mset9-chorus to an include, that logic doesn't work in VitePress
- Removed Get Started button from homepage, it breaks translations
- Tables in get-started are now shown by default; it seems VitePress really does
  not want us to use inline script. So we cannot enable it upon
  realizing that the browser is JS capable
- Include parameters are now in frontmatter to allow translation
- Hacked in a bunch of CSS values kanged from the old theme to make it
  look not stupid
- Drop headers down one level to make table of contents work

docs/get-started.md

@@ -1,39 +1,38 @@
 ---
-title: "Get Started"
+noneSelected: System model is required.
+invalidVersion: This doesn't seem to be a valid system version.
+head: [
+    ['script', {src: '/assets/js/selecting.js'}]
+]
 ---
 
-{% include toc title="Table of Contents" %}
+# Get Started
 
 Before starting this guide, we will see if custom firmware is already installed and check the current system version of your console.
 
-#### Section I - CFW Check
+### Section I - CFW Check
 
 1. Power off your console
 1. Hold the (Select) button
 1. Power on your console while still holding the (Select) button
 1. If you do not see a custom menu (your console just boots to the HOME Menu), you may proceed to the next section
 
-If you see the Luma3DS configuration screen or any other custom menu (e.g. GodMode9, Decrypt9WIP), STOP - you already have custom firmware! Continue from [here](checking-for-cfw#what-to-do-next).
-{: .notice--warning}
+::: warning
 
-#### Section II - System Version Check
+If you see the Luma3DS configuration screen or any other custom menu (e.g. GodMode9, Decrypt9WIP), STOP - you already have custom firmware! Continue from [here](checking-for-cfw#what-to-do-next).
+
+:::
+
+### Section II - System Version Check
 
 1. Launch System Settings on your console
 1. Your system version will be displayed on the bottom right of the top screen (e.g. "Ver. 11.17.0-50U")
 
-#### Section III - Select a Method
+### Section III - Select a Method
 
 To find the correct method for your console, please select the model of your console and the system version you found in Section II.
 
-{% capture noneSelected %}
-System model is required.
-{% endcapture %}
-
-{% capture invalidVersion %}
-This doesn't seem to be a valid system version.
-{% endcapture %}
-
-{% include consoleVersionSelect.html noneSelected=noneSelected invalidVersion=invalidVersion methodUnavailable=methodUnavailable %}
+<!--@include: @/_internal/consoleVersionSelect.html -->
 
 ---