refactor(stats-daemon): split into cpu/mem/temp/gpu modules, add gpu support

stats-daemon/src/temp.rs

@@ -0,0 +1,25 @@
+use std::fs;
+use std::io::Write;
+
+pub fn read_temp_celsius() -> Option<i32> {
+    let mut max: Option<i32> = None;
+    for i in 0.. {
+        let path = format!("/sys/class/thermal/thermal_zone{i}/temp");
+        match fs::read_to_string(&path) {
+            Ok(s) => {
+                if let Ok(millic) = s.trim().parse::<i32>() {
+                    let c = millic / 1000;
+                    max = Some(max.map_or(c, |m: i32| m.max(c)));
+                }
+            }
+            Err(_) => break,
+        }
+    }
+    max
+}
+
+pub fn emit_temp(out: &mut impl Write) {
+    if let Some(c) = read_temp_celsius() {
+        let _ = writeln!(out, "{{\"type\":\"temp\",\"celsius\":{c}}}");
+    }
+}