feat: add uptime to title

it will be displayed somewhere else later,
hopefully with better formatting too.

src/sysinfo_snapshot.rs

@@ -1,5 +1,9 @@
+use std::time::Duration;
+
 #[derive(Clone, Debug)]
 pub struct SysinfoSnapshot {
+    uptime: u64,
+
     pub cpu_total: f32,
     pub cpus: Vec<f32>,
 
@@ -8,10 +12,17 @@ pub struct SysinfoSnapshot {
     pub swap: u64,
     pub swap_total: u64,
 }
+impl SysinfoSnapshot {
+    pub fn uptime(&self) -> Duration {
+        Duration::from_secs(self.uptime)
+    }
+}
 
 impl From<&sysinfo::System> for SysinfoSnapshot {
     fn from(value: &sysinfo::System) -> Self {
         Self {
+            uptime: sysinfo::System::uptime(),
+
             cpu_total: value.global_cpu_usage(),
             cpus: value.cpus().iter().map(|cpu| cpu.cpu_usage()).collect(),