Campaign mission system: 20 mission definitions, goals, unlocks, carry-over

- campaign.rs: missions as key data (size, rivers, fortresses, goals, waves, time limit, gifts);
  start_mission builds the map with the generator; tools unlock step by step; the strongest
  5 creatures and 20% of the gold are carried into the next mission; campaign progress type
- Map generator options (portals, treasure caves, hero gate) and meandering rivers with
  knight bridges
- Mission goals: shards, gate of the order, all knights, vault loot, knight towers, waves;
  time limits; waves and gate defenders only where the mission wants them
- Locked tools are shown dark and cannot be chosen; HUD shows gate/waves/time only when used
- Fix: patrol routes no longer start on tower spots
- Tests: every mission builds, its goals are possible, wave heroes reach the core

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

src/fortress.rs

@@ -157,7 +157,8 @@ impl Game {
             e.home = Some((hx, hy));
         }
         // patrols: round through the courtyard along the inside of the walls
-        let route = vec![(x0 + 2, cy), (cx, y0 + 2), (x1 - 2, cy), (cx, y1 - 2)];
+        // (next to the tower spots in the middle of the walls)
+        let route = vec![(x0 + 3, cy + 2), (cx + 2, y0 + 3), (x1 - 3, cy - 2), (cx - 2, y1 - 3)];
         let route: Vec<(i32, i32)> = route.into_iter().filter(|&(x, y)| self.map.walk(x, y)).collect();
         for (g, group) in f.patrols.iter().enumerate() {
             if route.is_empty() {