feat: track Decman configuration

system-config/hosts.py

@@ -0,0 +1,32 @@
+"""Machine profiles compose concerns; concerns never depend on a host."""
+
+from modules.host_system import desktop_system, laptop_system
+from modules.packages import PackageConcern
+
+COMMON = (
+    "common/core",
+    "common/wayland",
+    "common/fonts",
+    "common/development",
+    "common/productivity",
+    "common/media",
+    "common/research",
+    "common/network",
+    "common/services",
+)
+LAPTOP = ("laptop/hardware",)
+DESKTOP = ()
+
+
+def _concerns(names: tuple[str, ...]) -> list[PackageConcern]:
+    return [PackageConcern(name) for name in names]
+
+
+def laptop() -> list:
+    """Laptop: shared concerns, laptop hardware, and laptop system configuration."""
+    return [*_concerns((*COMMON, *LAPTOP)), *laptop_system()]
+
+
+def desktop() -> list:
+    """Future desktop: shared concerns plus desktop-only concerns when declared."""
+    return [*_concerns((*COMMON, *DESKTOP)), *desktop_system()]