Add digging tasks and unit coordinate support

Introduce Tasks handling for units, store coordinates in MinerUnit,
expose getters/setters for unit tasks, add logging of marked cells,
and provide cell accessors for mutable unit options.

src/app/states/skirmish_states/units/unit_trait.rs

@@ -1,4 +1,4 @@
-use crate::app::states::skirmish_states::Players;
+use crate::app::states::skirmish_states::{Players, tasks::Tasks};
 use ratatui::{
     style::Stylize,
     text::{Line, Span},
@@ -23,6 +23,10 @@ pub trait Unit {
 
     fn get_digging_power(&self) -> f32;
 
+    fn get_coords(&self) -> (usize, usize);
+
+    fn set_task(&mut self, task: Tasks);
+
     fn base_text(&self) -> Vec<Line<'_>> {
         let owner: Span<'_> = self.get_owner().get_span();
         let hp: u16 = self.get_hp();