CI: add rust/ build+test workflow

data/dungeons/mangar_5.json

@@ -0,0 +1,31 @@
+{
+  "id": "mangar_5",
+  "name": "Mangar's Tower - Level 5 (Throne Room)",
+  "dungeon": "mangar",
+  "level": 5,
+  "width": 22,
+  "height": 22,
+  "description": "Mangar's Throne Room. The final battle. Defeat Mangar the Dark to break the curse on Skara Brae and free the city from eternal winter.",
+  "encounter_level": 8,
+  "special_squares": [
+    { "x": 0, "y": 0, "type": "stairs_up", "destination": "mangar_4", "label": "Return to Mangar's Tower Level 4" },
+    { "x": 11, "y": 11, "type": "special_encounter", "text": "MANGAR THE DARK! The archmage who cursed Skara Brae sits upon his throne of bone and shadow!", "encounter": "mangar" },
+    { "x": 5, "y": 3, "type": "special_encounter", "text": "Mangar summons his Black Dragon to defend the throne!", "encounter": "mangar_black_dragon" },
+    { "x": 16, "y": 3, "type": "special_encounter", "text": "Mangar's Demon Lord bodyguard attacks!", "encounter": "mangar_demon_lord" },
+    { "x": 3, "y": 8, "type": "anti_magic", "text": "Mangar's absolute anti-magic field. Only the strongest magic can penetrate." },
+    { "x": 18, "y": 8, "type": "trap", "text": "Mangar casts Meteor Shower! Explosions rock the throne room!", "damage": "6d8" },
+    { "x": 9, "y": 6, "type": "darkness", "text": "Mangar plunges the room into supernatural darkness." },
+    { "x": 14, "y": 6, "type": "silence", "text": "Mangar's Word of Power silences all sound and song." },
+    { "x": 7, "y": 14, "type": "special_encounter", "text": "Mangar summons undead reinforcements!", "encounter": "mangar_undead" },
+    { "x": 16, "y": 14, "type": "trap", "text": "Mangar's Disintegrate spell targets the party!", "damage": "4d10" },
+    { "x": 11, "y": 3, "type": "message", "text": "Mangar's voice echoes: 'Fools! You dare challenge ME? I am eternal!'" },
+    { "x": 11, "y": 19, "type": "message", "text": "Victory! Mangar falls! The curse on Skara Brae begins to break. The snow melts..." },
+    { "x": 4, "y": 18, "type": "trap", "text": "Mangar's final spite - a death curse as he falls!", "damage": "5d8" },
+    { "x": 18, "y": 18, "type": "special_encounter", "text": "Mangar's Lich advisor makes a last stand!", "encounter": "mangar_lich" },
+    { "x": 8, "y": 11, "type": "message", "text": "Mangar's throne radiates power. Destroying it will break the curse forever." },
+    { "x": 14, "y": 11, "type": "message", "text": "The walls of the throne room are inscribed with the spell of eternal winter." }
+  ],
+  "connections": [
+    { "from_x": 0, "from_y": 0, "to": "mangar_4", "type": "stairs_up" }
+  ]
+}