fix Allium specs syntax + implement Changing Level story

- Fix Allium spec syntax: type→value, enum for Status, remove implies chaining
- Fix factions.spec: add missing type declarations (Health, Level, Status)
- Fix magical-objects.spec: add type declarations, use .value for Health access,
  remove entity inheritance syntax, remove invalid invariants
- Implement Changing Level: add totalDamageTaken + factionsJoined to Character
- Add level-up logic in dealDamage() and joinFaction()
- Add Level.damageThresholdForLevel() static method
- Fix changing-level.spec.ts properties: handle target survival, compute
  expected level from threshold crossings

src/value-objects/Level.ts

@@ -37,6 +37,6 @@ export class Level {
    *  Formula: 1000 * N * (N+1) / 2
    */
   static damageThresholdForLevel(level: number): number {
-    return 1000 * level * (level + 1) / 2;
+    return (1000 * level * (level + 1)) / 2;
   }
 }