Add init flags to Offset and set vertical offset

Add `value_initiated` and `max_initiated` flags to prevent
repeated assignments. Provide `set_initial_value` for one‑time
initialisation and use it to centre the vertical offset when
creating the board widget. Remove stale comments on cell size constants.

src/app/states/skirmish.rs

@@ -5,23 +5,40 @@ use clap::ValueEnum;
 pub struct Offset {
     value: usize,
     max: usize,
+    value_initiated: bool,
+    max_initiated: bool,
 }
 
 impl Offset {
     pub fn new() -> Self {
-        Self { value: 0, max: 0 }
+        Self {
+            value: 0,
+            max: 0,
+            value_initiated: false,
+            max_initiated: false,
+        }
     }
 
     pub fn get_value(&self) -> usize {
         self.value
     }
 
+    pub fn set_initial_value(&mut self, value: usize) {
+        if self.value_initiated {
+            return;
+        }
+
+        self.value = value;
+        self.value_initiated = true;
+    }
+
     pub fn set_max(&mut self, max: usize) {
-        if self.max != 0 {
+        if self.max_initiated {
             return;
         }
 
         self.max = max;
+        self.max_initiated = true;
     }
 
     pub fn next(&mut self) {

src/app/widgets/board.rs

@@ -19,8 +19,8 @@ pub struct BoardWidget<'a> {
 
 impl<'a> BoardWidget<'a> {
     pub fn new(app: &'a mut App, area_width: u16, area_height: u16) -> Self {
-        const CELL_HIGHT: u16 = 5; // 4
-        const CELL_WIDTH: u16 = 9; // 7
+        const CELL_HIGHT: u16 = 5;
+        const CELL_WIDTH: u16 = 9;
 
         let rows: u16 = area_height / CELL_HIGHT;
         let cols: u16 = area_width / CELL_WIDTH;
@@ -40,6 +40,13 @@ impl<'a> BoardWidget<'a> {
         app.states.skirmish.horizontal_offset.set_max(h_max_offset);
         app.states.skirmish.vertical_offset.set_max(v_max_offset);
 
+        if v_max_offset > 0 {
+            app.states
+                .skirmish
+                .vertical_offset
+                .set_initial_value((app.states.skirmish.map_height - rows as usize) / 2);
+        }
+
         Self {
             map_width: app.states.skirmish.map_width as usize,
             cell_width: CELL_WIDTH,