fix: resolve React hooks violation in hardware settings

Moved getVideoSleepMode useEffect before early returns to comply with
React Rules of Hooks. All hooks must be called in the same order on
every component render, before any conditional returns.

This completes the merge from dev branch, preserving both:
- Permission-based access control from multi-session branch
- HDMI sleep mode power saving feature from dev branch

ui/src/routes/devices.$id.settings.hardware.tsx

@@ -94,6 +94,17 @@ export default function SettingsHardwareRoute() {
     }
   }, [send, setBacklightSettings, isLoading, permissions]);
 
+  useEffect(() => {
+    send("getVideoSleepMode", {}, (resp: JsonRpcResponse) => {
+      if ("error" in resp) {
+        console.error("Failed to get power saving mode:", resp.error);
+        return;
+      }
+      const result = resp.result as { enabled: boolean; duration: number };
+      setPowerSavingEnabled(result.duration >= 0);
+    });
+  }, [send]);
+
   // Return early if permissions are loading
   if (isLoading) {
     return (
@@ -112,17 +123,6 @@ export default function SettingsHardwareRoute() {
     );
   }
 
-  useEffect(() => {
-    send("getVideoSleepMode", {}, (resp: JsonRpcResponse) => {
-      if ("error" in resp) {
-        console.error("Failed to get power saving mode:", resp.error);
-        return;
-      }
-      const result = resp.result as { enabled: boolean; duration: number };
-      setPowerSavingEnabled(result.duration >= 0);
-    });
-  }, [send]);
-
   return (
     <div className="space-y-4">
       <SettingsPageHeader