Five new rooms: prison, graveyard, guard post, arena, sacrifice altar; new creature: the revenant

- prison: captured heroes sit in cells apart from the torture chamber, do not defect and starve in time; the hand can move prisoners between cells and torture
- graveyard: the fallen are buried there; after a while some rise as revenants (undead: no food, no sleep, life drain from level 5)
- guard post: creatures hold the position and attack whatever comes into view
- arena: creatures spar in pairs for fast, free experience, at the cost of bruises
- sacrifice altar: creatures dropped on it are sacrificed; certain pairs bring a rare creature, otherwise a blessing (mood and mana)
- researched in the library, campaign unlocks, textures, furniture, texts EN/DE, bestiary

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

src/research.rs

@@ -15,7 +15,9 @@ pub const RESEARCH: &[(usize, f32)] = &[
     (29, 250.0),  // wooden door
     (32, 300.0),  // seer's eye
     (15, 400.0),  // cannon tower
+    (42, 300.0),  // guard post
     (12, 450.0),  // torture chamber
+    (40, 450.0),  // prison
     (26, 300.0),  // alarm bell
     (35, 400.0),  // stoneskin
     (11, 500.0),  // summon
@@ -24,6 +26,8 @@ pub const RESEARCH: &[(usize, f32)] = &[
     (30, 500.0),  // iron door
     (33, 550.0),  // cave-in
     (18, 550.0),  // aerie
+    (43, 550.0),  // arena
+    (41, 600.0),  // graveyard
     (16, 650.0),  // magic tower
     (36, 600.0),  // gold rain
     (24, 650.0),  // fire jet
@@ -34,6 +38,7 @@ pub const RESEARCH: &[(usize, f32)] = &[
     (38, 850.0),  // plague
     (27, 900.0),  // rune mine
     (39, 950.0),  // quake
+    (44, 900.0),  // sacrifice altar
     (31, 1100.0), // magic door
 ];