feat: add install command

Not wired yet

src/caelestia/utils/dots/state.py

@@ -0,0 +1,51 @@
+import json
+from dataclasses import dataclass, field
+
+from caelestia.utils.io import warn
+from caelestia.utils.paths import atomic_dump, dots_state_path
+
+
+@dataclass
+class DotsState:
+    # The AUR helper selected selected at install time
+    aur_helper: str = "paru"
+
+    # The git rev of currently applied dots version
+    applied_rev: str | None = None
+
+    # The currently enabled components
+    enabled_components: list[str] = field(default_factory=list)
+
+    # Previously installed packages/local packages
+    packages: list[str] = field(default_factory=list)
+    local_packages: dict[str, list[str]] = field(default_factory=dict)
+
+    @staticmethod
+    def load() -> "DotsState":
+        try:
+            data = json.loads(dots_state_path.read_text())
+        except FileNotFoundError:
+            return DotsState()
+        except json.JSONDecodeError:
+            warn("failed to parse current dots state.")
+            return DotsState()
+
+        return DotsState(
+            aur_helper=data.get("aur_helper"),
+            applied_rev=data.get("applied_rev"),
+            enabled_components=data.get("enabled_components", []),
+            packages=data.get("packages", []),
+            local_packages=data.get("local_packages", {}),
+        )
+
+    def save(self) -> None:
+        atomic_dump(
+            dots_state_path,
+            {
+                "aur_helper": self.aur_helper,
+                "applied_rev": self.applied_rev,
+                "enabled_components": self.enabled_components,
+                "packages": self.packages,
+                "local_packages": self.local_packages,
+            },
+        )