CI: add rust/ build+test workflow

data/dungeons/catacombs_3.json

@@ -0,0 +1,30 @@
+{
+  "id": "catacombs_3",
+  "name": "Catacombs - Level 3",
+  "dungeon": "catacombs",
+  "level": 3,
+  "width": 22,
+  "height": 22,
+  "description": "The deepest catacombs. This level connects to Harkyn's Castle. Powerful undead and dark magic pervade every corner.",
+  "encounter_level": 3,
+  "special_squares": [
+    { "x": 0, "y": 0, "type": "stairs_up", "destination": "catacombs_2", "label": "Return to Catacombs Level 2" },
+    { "x": 21, "y": 21, "type": "stairs_down", "destination": "harkyn_1", "label": "Descend to Harkyn's Castle" },
+    { "x": 11, "y": 11, "type": "special_encounter", "text": "A powerful lich guards the bridge to Harkyn's domain!", "encounter": "catacomb_lich" },
+    { "x": 5, "y": 3, "type": "trap", "text": "A necromantic trap drains your life force!", "damage": "2d8" },
+    { "x": 16, "y": 5, "type": "anti_magic", "text": "The lich's phylactery nearby suppresses all magic in this area." },
+    { "x": 3, "y": 8, "type": "darkness", "text": "Total darkness. You hear chanting in a language you don't recognize." },
+    { "x": 18, "y": 10, "type": "spinner", "text": "The magical maze shifts around you. Walls move when you're not looking." },
+    { "x": 8, "y": 14, "type": "silence", "text": "A zone of absolute silence enforced by dark runes." },
+    { "x": 14, "y": 16, "type": "trap", "text": "Spectral hands reach from the walls and drain your vitality!", "damage": "1d10" },
+    { "x": 6, "y": 18, "type": "message", "text": "Ancient prophecy carved in stone: 'When the seven sleep, Skara Brae shall be free.'" },
+    { "x": 19, "y": 7, "type": "special_encounter", "text": "A ghost appears and points toward Harkyn's Castle!", "encounter": "benevolent_ghost" },
+    { "x": 10, "y": 19, "type": "message", "text": "The passage to Harkyn's Castle is behind a massive stone door." },
+    { "x": 2, "y": 12, "type": "darkness", "text": "Shadow creatures dart at the edge of your vision." },
+    { "x": 15, "y": 3, "type": "trap", "text": "A pressure plate triggers a cascade of bones!", "damage": "1d6" }
+  ],
+  "connections": [
+    { "from_x": 21, "from_y": 21, "to": "harkyn_1", "type": "stairs_down" },
+    { "from_x": 0, "from_y": 0, "to": "catacombs_2", "type": "stairs_up" }
+  ]
+}