feat: add cpu temp widget

widgets/bar/cpu.tsx

@@ -0,0 +1,15 @@
+import { bind, Variable } from "astal";
+
+export const CPU = () => {
+  const cpu = Variable("").poll(5000, [
+    "bash",
+    "-c",
+    "cat /sys/class/thermal/thermal_zone*/temp",
+  ]);
+
+  return (
+    <box cssClasses={["pill"]}>
+      <label label={bind(cpu).as((val) => `CPU: ${parseInt(val) / 1000} °C`)} />
+    </box>
+  );
+};