feat: mudfish client and connect/disconnect controller

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

py_modules/mudfish_decky/store.py

@@ -0,0 +1,28 @@
+"""Plugin settings persisted as JSON."""
+import json
+import os
+
+
+class Store:
+    def __init__(self, path: str):
+        self.path = path
+
+    def load(self) -> dict:
+        try:
+            with open(self.path) as f:
+                return json.load(f)
+        except (OSError, ValueError):
+            return {}
+
+    def save(self, data: dict) -> None:
+        os.makedirs(os.path.dirname(self.path) or ".", exist_ok=True)
+        tmp = self.path + ".tmp"
+        with open(tmp, "w") as f:
+            json.dump(data, f)
+        os.replace(tmp, self.path)
+
+    def update(self, **changes) -> dict:
+        data = self.load()
+        data.update(changes)
+        self.save(data)
+        return data