feat: m3 kampf, events und trigger

Der Dungeon hat jetzt Gegner, und man kann sterben.

- game/action.rs: sieben Schadenstypen, fuenf der zehn Aktionen, Target
- game/condition.rs: Bedingungsgrammatik (Liste = UND, not je Eintrag)
- game/event.rs: zwoelf Events, Trigger als vierte Wirkungsform
- game/combat.rs: Treffer- und Schadensformel mit drei Klemmbereichen
- Game::apply, drain_events (FIFO), Initiative, Rundenablauf aus Ticket 14
- data/: abilities-, creatures- und modifiers-Registry, [balance] feldweise
- ui/: Combat-Screen mit Faehigkeitsmenue und Sperrgrund

Drei Befunde:
- Die Trefferformel war toter Code — jeder Angriff traf. Nur der Compiler
  hat es gemeldet ('hit_chance is never used'). Test haelt sie am Leben.
- Die Warteschlange war ein Stack (pop statt pop_front), obwohl Ticket 08
  ausdruecklich 'haengt es hinten an' sagt. Jetzt VecDeque.
- Benannte Modifikatoren (core:poisoned) hatten keine Registry — Ticket 01
  laesst apply_modifier per ID referenzieren, aber keine der zwoelf
  definierte sie. Das ist die dreizehnte.

43 Tests.

mods/core/floors.toml

@@ -15,6 +15,7 @@ size     = [72, 34]
 rooms    = 7
 required = ["core:entrance", "core:stairs", "core:merchant"]
 prefabs  = [ { tag = "core:normal", weight = 10 } ]
+creatures = [ { id = "core:rat", weight = 10 } ]
 
 [[floors]]
 id       = "floor_2"
@@ -24,6 +25,7 @@ rooms    = 8
 required = ["core:entrance", "core:stairs", "core:merchant"]
 prefabs  = [ { tag = "core:normal", weight = 10 },
              { tag = "core:treasure", weight = 2 } ]
+creatures = [ { id = "core:rat", weight = 6 }, { id = "core:skeleton", weight = 6 } ]
 
 [[floors]]
 id       = "floor_3"
@@ -33,6 +35,7 @@ rooms    = 9
 required = ["core:entrance", "core:stairs", "core:merchant"]
 prefabs  = [ { tag = "core:normal", weight = 10 },
              { tag = "core:treasure", weight = 3 } ]
+creatures = [ { id = "core:rat", weight = 3 }, { id = "core:skeleton", weight = 8 }, { id = "core:ghoul", weight = 3 } ]
 
 [[floors]]
 id       = "floor_4"
@@ -42,6 +45,7 @@ rooms    = 10
 required = ["core:entrance", "core:stairs", "core:merchant"]
 prefabs  = [ { tag = "core:normal", weight = 10 },
              { tag = "core:treasure", weight = 3 } ]
+creatures = [ { id = "core:skeleton", weight = 6 }, { id = "core:ghoul", weight = 8 } ]
 
 [[floors]]
 id       = "floor_5"
@@ -51,3 +55,4 @@ rooms    = 11
 required = ["core:entrance", "core:stairs", "core:merchant"]
 prefabs  = [ { tag = "core:normal", weight = 10 },
              { tag = "core:treasure", weight = 4 } ]
+creatures = [ { id = "core:ghoul", weight = 8 }, { id = "core:bone_lord", weight = 2 } ]