feat: cite a folder for every handheld row

Allium, JELOS, KOLOS and MiyooCFW folders come from their own trees at the revision the installer reads. Rows with no cited folder point at RetroArch's System/BIOS setting, and a folder only Linux reads says so. KNULLI's SAMBA switch is linked, AmberELEC's roms share is named, the MinUI family says the command makes each folder, and an iPhone and iPad tile joins the handheld group.

scripts/siteguides.py

@@ -91,6 +91,7 @@ class HandheldSystem:
     folder_source: str = ""
     devices: tuple[str, ...] = ()
     devices_source: str = ""
+    linux_only: bool = False
 
 
 @dataclass(frozen=True)
@@ -125,7 +126,7 @@ _GROUP_KEYS = {"label", "description", "anchor", "also_runs", "tiles"}
 _ALSO_KEYS = ("setup", "summary", "uses", "runs_on", "folder")
 _TILE_KEYS = ("name", "text", "link")
 _HANDHELD_KEYS = {"page", "title", "summary", "uses", "systems"}
-_SYSTEM_KEYS = {"name", "folder", "folder_source", "devices", "devices_source"}
+_SYSTEM_KEYS = {"name", "folder", "folder_source", "devices", "devices_source", "linux_only"}
 _SOURCE = re.compile(r"https://\S+")
 _TERMINAL_KEYS = ("label", "how", "shell")
 
@@ -239,6 +240,10 @@ def _handheld_system(data: object, where: str) -> HandheldSystem:
             values[value] = (_texts(data[value], f"{where}.{value}") if value == "devices"
                              else _text(data[value], f"{where}.{value}"))
             values[source] = _source(data[source], f"{where}.{source}")
+    if "linux_only" in data:
+        if not isinstance(data["linux_only"], bool) or "folder" not in data:
+            raise GuideError(f"{where}.linux_only: expected true or false, with a folder")
+        values["linux_only"] = data["linux_only"]
     return HandheldSystem(**values)