Replace CellTag with CellStructure and embed BaseBuilding

The refactor removes the `Buildings` enum and the `building` module,
replacing
`CellTag` with a new `CellStructure` enum that directly holds a
`BaseBuilding`.
A `get_owner` method is added to `BaseBuilding` to support the new
structure.
All related imports, constructors, and rendering logic are updated to
use
`CellStructure` instead of the old tag and building fields.

src/app/widgets/cell.rs

@@ -1,6 +1,5 @@
 use crate::app::{
-    buildings::Buildings,
-    states::{CellTag, Players, ZoomLevel},
+    states::{CellStructure, Players, ZoomLevel},
     units::Units,
 };
 use ratatui::{
@@ -17,10 +16,9 @@ pub struct CellWidget {
     col: usize,
     selected: bool,
     zoom_level: ZoomLevel,
-    tag: CellTag,
+    structure: CellStructure,
     marked: bool,
     unit: Option<Units>,
-    building: Option<Buildings>,
 }
 
 impl CellWidget {
@@ -29,19 +27,17 @@ impl CellWidget {
         col: usize,
         zoom_level: ZoomLevel,
         selected: bool,
-        tag: CellTag,
+        structure: CellStructure,
         unit: Option<Units>,
-        building: Option<Buildings>,
     ) -> Self {
         Self {
             row,
             col,
             selected,
             zoom_level,
-            tag,
             marked: false,
+            structure,
             unit,
-            building,
         }
     }
 
@@ -54,8 +50,8 @@ impl CellWidget {
         self.zoom_level = zoom_level;
     }
 
-    pub fn set_tag(&mut self, tag: CellTag) {
-        self.tag = tag;
+    pub fn set_structure(&mut self, sctructure: CellStructure) {
+        self.structure = sctructure;
     }
 
     pub fn get_marked(&self) -> bool {
@@ -80,7 +76,7 @@ impl CellWidget {
     }
 
     fn display_coords(&self) -> Span<'_> {
-        if self.selected || self.tag != CellTag::Stone || self.marked {
+        if self.selected || self.structure != CellStructure::Stone || self.marked {
             format!("{}{}", self.col_to_letters(), self.row).green()
         } else {
             "".to_span()
@@ -88,36 +84,30 @@ impl CellWidget {
     }
 
     fn fg_color(&self) -> Color {
-        match self.tag {
+        match self.structure {
             _ if self.marked && self.selected => Color::Magenta,
             _ if self.marked && !self.selected => Color::LightMagenta,
             _ if self.selected && !self.marked => Color::LightYellow,
-            CellTag::Base(Players::Player) if !self.selected => Color::LightBlue,
-            CellTag::Base(Players::Enemy) if !self.selected => Color::LightRed,
-            CellTag::Tunel if !self.selected => Color::Gray,
+            CellStructure::Base(base) if !self.selected => match base.get_owner() {
+                Players::Player => Color::LightBlue,
+                Players::Enemy => Color::LightRed,
+            },
+            CellStructure::Tunel if !self.selected => Color::Gray,
             _ => Color::White,
         }
     }
 
     fn get_text_area(&self) -> Vec<Line<'_>> {
-        let tag: &str = match self.building {
-            Some(building) => match building {
-                Buildings::Base(base) => base.get_tag(),
-                // _ => " ",
-            },
-            None => match self.tag {
-                CellTag::Tunel => "T",
-                CellTag::Stone => " ",
-                _ => " ",
-            },
+        let tag: &str = match self.structure {
+            CellStructure::Base(base) => base.get_tag(),
+            CellStructure::Tunel => "T",
+            CellStructure::Stone => " ",
+            // _ => " ",
         };
 
-        let b_level: &str = match self.building {
-            Some(building) => match building {
-                Buildings::Base(base) => base.get_level(),
-                // _ => " ",
-            },
-            None => " ",
+        let b_level: &str = match self.structure {
+            CellStructure::Base(base) => base.get_level(),
+            _ => " ",
         };
 
         let unit: &str = match self.unit {