Steel walls: plate earth walls next to own ground with steel

- New tool Steel (key O, orders category; campaign from mission 11): 80 gold per earth wall,
  40 for a reinforced wall; riveted iron plate texture
- Heroes dig through steel 20 times slower than through earth and avoid it (path cost 300)
- Selling turns a steel wall back into a reinforced wall and refunds half the plating
- Texts EN/DE, test

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/ui.rs

@@ -156,10 +156,11 @@ pub enum Tool {
     Summon,
     Tower(TowerKind),
     Bridge,
+    Steel,
 }
 
 // New tools are appended so that existing key bindings ("tool<i>") keep their meaning
-pub const TOOLS: [Tool; 19] = [
+pub const TOOLS: [Tool; 20] = [
     Tool::Dig,
     Tool::Hand,
     Tool::Room(0),
@@ -179,6 +180,7 @@ pub const TOOLS: [Tool; 19] = [
     Tool::Tower(TowerKind::Magic),
     Tool::Bridge,
     Tool::Room(7),
+    Tool::Steel,
 ];
 
 
@@ -210,6 +212,7 @@ pub fn tool_info(t: Tool) -> ToolInfo {
         Tool::Heal => ("heal", I_HEAL, None),
         Tool::Summon => ("summon", I_SUMMON, None),
         Tool::Bridge => ("bridge", I_BRIDGE, None),
+        Tool::Steel => ("steel", I_STEEL, None),
     };
     let name = match room {
         Some(r) => tr(ROOM_NAMES[r]),
@@ -225,6 +228,7 @@ pub fn tool_cost(t: Tool, g: &Game) -> String {
         Tool::Heal => trf("cost.mana", &["60".into()]),
         Tool::Summon => trf("cost.mana", &[(g.summon_cost() as i32).to_string()]),
         Tool::Bridge => trf("cost.bridge", &[BRIDGE_COST[0].to_string(), BRIDGE_COST[1].to_string()]),
+        Tool::Steel => trf("cost.steel", &[STEEL_COST[0].to_string(), STEEL_COST[1].to_string()]),
         Tool::Tower(k) => {
             let s = tower_stats(k);
             let mut c = trf("cost.tower", &[s.cost[0].to_string(), s.cost[1].to_string(), s.cost[2].to_string()]);
@@ -244,7 +248,7 @@ pub const CATS: [(&str, &[usize]); 6] = [
     ("cat.rooms", &[2, 3, 4, 5, 6, 12, 13, 18, 17]),
     ("cat.towers", &[14, 15, 16]),
     ("cat.spells", &[9, 10, 11]),
-    ("cat.orders", &[8, 7]),
+    ("cat.orders", &[8, 7, 19]),
 ];
 
 #[derive(Clone, Copy, PartialEq, Debug)]
@@ -1061,6 +1065,10 @@ pub fn hover_info(g: &Game, ent: Option<usize>, tile: Option<(i32, i32)>) -> Vec
     };
     match t.kind {
         Kind::Rock => out.push((tr("tile.rock"), DIM)),
+        Kind::Steel => {
+            out.push((tr("tile.steel"), FRAME_HI));
+            out.push((tr("tile.steel_info"), DIM));
+        }
         Kind::Earth if t.reinforced => {
             out.push((tr("tile.reinforced"), FRAME_HI));
             out.push((tr("tile.reinforced_info"), DIM));