fix: read extract folders from the registry

tests/test_extract_targets.py

@@ -0,0 +1,60 @@
+"""Where a pack extracts is read from the registry, by the README and the site.
+
+Both kept a hand table keyed by display name. RomM's row said
+`bios/{platform_slug}/` while the pack already carries one folder per slug
+at its root, so following it nested every file one level too deep. The
+README's RetroDECK sentence sat inside the archived-platforms block and
+would have vanished the day RetroPie became active again.
+"""
+
+from __future__ import annotations
+
+import sys
+import unittest
+from pathlib import Path
+
+REPO_ROOT = Path(__file__).resolve().parent.parent
+sys.path.insert(0, str(REPO_ROOT / "scripts"))
+
+from common import load_platform_config, load_platform_registry
+from generate_readme import extract_notes, extract_targets
+
+PLATFORMS = str(REPO_ROOT / "platforms")
+
+
+class ExtractTargets(unittest.TestCase):
+    def test_every_registered_platform_says_where_it_extracts(self):
+        registry = load_platform_registry(PLATFORMS)
+        missing = sorted(k for k, v in registry.items() if not v.get("extract_to"))
+        self.assertEqual(missing, [])
+        self.assertEqual(len(extract_targets(PLATFORMS)), len(registry))
+
+    def test_a_folder_names_no_placeholder(self):
+        """The pack lays out the per-system folders itself."""
+        templated = [d for d, folder in extract_targets(PLATFORMS) if "{" in folder]
+        self.assertEqual(templated, [])
+
+    def test_a_pack_with_its_own_root_is_explained_whatever_is_archived(self):
+        rooted = sorted(
+            load_platform_config(key, PLATFORMS).get("platform", key)
+            for key in load_platform_registry(PLATFORMS)
+            if load_platform_config(key, PLATFORMS).get("base_destination") == ""
+        )
+        explained = sorted(
+            display for display in rooted
+            if any(note.startswith(f"The {display} pack") for note in extract_notes(PLATFORMS))
+        )
+        self.assertTrue(rooted)
+        self.assertEqual(explained, rooted)
+
+    def test_no_generator_keeps_its_own_table(self):
+        """The which-pack page describes setups per OS; these two were the
+        per-platform copies of the registry."""
+        readme = (REPO_ROOT / "scripts" / "generate_readme.py").read_text(encoding="utf-8")
+        site = (REPO_ROOT / "scripts" / "generate_site.py").read_text(encoding="utf-8")
+        self.assertNotIn('"RetroDECK": "`~/retrodeck/`"', readme)
+        self.assertNotIn('"    | RetroDECK | `~/retrodeck/` |"', site)
+
+
+if __name__ == "__main__":
+    unittest.main()