Fix wrapped command if not full year

If atuin has not been used the whole year, then the "Command Evolution"
will be misleading, as the year is split 182 days after the first command.

This change set the mid-point of the year midways between the first and
last command in the year.

crates/atuin/src/command/client/wrapped.rs

@@ -89,7 +89,11 @@ impl WrappedStats {
 
         // Error analysis
         let mut command_errors: HashMap<String, (usize, usize)> = HashMap::new(); // (total_uses, errors)
-        let midyear = history[0].timestamp + Duration::days(182); // Split year in half
+
+        // Find number of days commands have been collected
+        let days =
+            (history[history.len() - 1].timestamp.ordinal() - history[0].timestamp.ordinal()) / 2;
+        let midyear = history[0].timestamp + Duration::days(days.into()); // Split year in half
 
         let mut first_half_commands: HashMap<String, usize> = HashMap::new();
         let mut second_half_commands: HashMap<String, usize> = HashMap::new();