Initial commit: Theriapolis baseline at port/godot branch point

Captures the pre-Godot-port state of the codebase. This is the rollback
anchor for the Godot port (M0 of theriapolis-rpg-implementation-plan-godot-port.md).
All Phase 0 through Phase 6.5 work is included; Phase 7 is in flight.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Content/Data/dungeon_layouts/imperium_medium.json

@@ -0,0 +1,27 @@
+{
+  "id": "imperium_medium",
+  "dungeon_type": "ImperiumRuin",
+  "size_band": "medium",
+  "anchor": "",
+  "room_count_min": 6,
+  "room_count_max": 10,
+  "branching": "branching",
+  "required_roles": ["entry", "boss"],
+  "optional_roles": ["narrative", "loot", "dead-end"],
+  "loot_table_per_band": {
+    "t1": "loot_dungeon_imperium_t1",
+    "t2": "loot_dungeon_imperium_t2",
+    "t3": "loot_dungeon_imperium_t3"
+  },
+  "spawn_kind_distribution": {
+    "PoiGuard":   0.7,
+    "WildAnimal": 0.2,
+    "Brigand":    0.1
+  },
+  "level_band_to_loot_band": {
+    "0": "t1",
+    "1": "t1",
+    "2": "t2",
+    "3": "t3"
+  }
+}