Add Task trait and improve miner task display

Define a full `Task` trait with icon and path accessors. Implement the
trait for
`DiggingTask` and delegate it through the `Tasks` enum. Introduce helper
functions in `MinerUnit` to convert coordinates to spreadsheet‑style
strings
and use them in a revamped `get_tasks_formatted`. Update the unit
rendering
logic to show the tasks queue only when tasks are present.

src/app/states/skirmish_states/tasks/digging.rs

@@ -1,5 +1,7 @@
 use std::collections::VecDeque;
 
+use crate::app::states::skirmish_states::tasks::Task;
+
 #[derive(Debug, Clone, PartialEq)]
 pub struct DiggingTask {
     path: VecDeque<(usize, usize)>,
@@ -10,3 +12,21 @@ impl DiggingTask {
         Self { path }
     }
 }
+
+impl Task for DiggingTask {
+    fn get_icon(&self) -> char {
+        '⛏'
+    }
+
+    fn get_path(&self) -> &VecDeque<(usize, usize)> {
+        &self.path
+    }
+
+    fn get_path_front_coords(&self) -> &(usize, usize) {
+        self.path.front().map_or(&(0, 0), |c| c)
+    }
+
+    fn get_path_back_coords(&self) -> &(usize, usize) {
+        self.path.back().map_or(&(0, 0), |c| c)
+    }
+}

src/app/states/skirmish_states/tasks/task_trait.rs

@@ -1 +1,11 @@
-pub trait Task {}
+use std::collections::VecDeque;
+
+pub trait Task {
+    fn get_icon(&self) -> char;
+
+    fn get_path(&self) -> &VecDeque<(usize, usize)>;
+
+    fn get_path_front_coords(&self) -> &(usize, usize);
+
+    fn get_path_back_coords(&self) -> &(usize, usize);
+}

src/app/states/skirmish_states/tasks/tasks_enum.rs

@@ -1,6 +1,34 @@
-use crate::app::states::skirmish_states::tasks::DiggingTask;
+use crate::app::states::skirmish_states::tasks::{DiggingTask, Task};
+use std::collections::VecDeque;
 
 #[derive(Debug, Clone, PartialEq)]
 pub enum Tasks {
     Digging(DiggingTask),
 }
+
+impl Tasks {
+    #[inline]
+    fn t(&self) -> &dyn Task {
+        match self {
+            Self::Digging(d) => d,
+        }
+    }
+}
+
+impl Task for Tasks {
+    fn get_icon(&self) -> char {
+        self.t().get_icon()
+    }
+
+    fn get_path(&self) -> &VecDeque<(usize, usize)> {
+        self.t().get_path()
+    }
+
+    fn get_path_front_coords(&self) -> &(usize, usize) {
+        self.t().get_path_front_coords()
+    }
+
+    fn get_path_back_coords(&self) -> &(usize, usize) {
+        self.t().get_path_back_coords()
+    }
+}