feat: add minui, nextui and myminui platforms

minarch hands every core SDCARD_PATH/Bios/<TAG> as its system directory
and opens no file in it. The scrapers read each pak's launch.sh (core,
tag, devices), each device's core makefile (the project a library is
built from: MyMinUI's dosbox_libretro.so is dosbox-pure) and the minarch
statement, at a pinned commit. The installer recognises the card from
.system/version.txt and refuses a folder inside it.

scripts/scraper/nextui_scraper.py

@@ -0,0 +1,30 @@
+#!/usr/bin/env python3
+"""Scraper for NextUI's pak list: the MinUI scraper on NextUI's repository."""
+
+from __future__ import annotations
+
+try:
+    from . import minui_scraper
+except ImportError:
+    import minui_scraper
+
+PLATFORM_NAME = "nextui"
+
+
+class Scraper(minui_scraper.Scraper):
+    """Pak scraper for NextUI."""
+
+    variant = minui_scraper.VARIANTS["nextui"]
+
+
+def main() -> None:
+    try:
+        from .base_scraper import scraper_cli
+    except ImportError:
+        from base_scraper import scraper_cli
+
+    scraper_cli(Scraper, "Scrape the NextUI pak list")
+
+
+if __name__ == "__main__":
+    main()