feat: major content expansion with essence and crystal sinks

- 6 zones (up from 3): Shadow Marshes, Volcanic Depths, Astral Void
- 18 bosses (up from 4): 3 per zone with zone-based sequential unlock
- 24 quests (up from 9): 3-4 per zone, reorganised by zone
- 15 adventurer tiers (up from 10): Shadow Assassin through Divine Champion
- 28 equipment pieces (up from 12): boss drops + purchasable with essence/crystals
- 24 upgrades (up from 13): crystal-cost upgrades + new adventurer upgrades
- 22 achievements (up from 14): new milestones for bosses, quests, gold, armies
- Purchasable equipment system: buy items directly with essence or crystals
- Crystal-cost upgrades: spend crystals on global and click power boosts
- Zone-based boss progression: defeating a zone's last boss unlocks the next zone

apps/api/src/data/zones.ts

@@ -19,6 +19,15 @@ export const DEFAULT_ZONES: Zone[] = [
     status: "locked",
     unlockBossId: "lich_queen",
   },
+  {
+    id: "shadow_marshes",
+    name: "The Shadow Marshes",
+    description:
+      "A vast, fog-choked wetland where the sun never fully rises. Dark magic seeps from the earth itself, and things far older than the kingdom lurk beneath the murky waters.",
+    emoji: "🌑",
+    status: "locked",
+    unlockBossId: "troll_king",
+  },
   {
     id: "frozen_peaks",
     name: "The Frozen Peaks",
@@ -28,4 +37,22 @@ export const DEFAULT_ZONES: Zone[] = [
     status: "locked",
     unlockBossId: "elder_dragon",
   },
+  {
+    id: "volcanic_depths",
+    name: "The Volcanic Depths",
+    description:
+      "A chain of active volcanoes whose caverns plunge deep into the earth's molten heart. Legendary forges burn here, tended by fire elementals who serve no master — yet.",
+    emoji: "🌋",
+    status: "locked",
+    unlockBossId: "bone_colossus",
+  },
+  {
+    id: "astral_void",
+    name: "The Astral Void",
+    description:
+      "Beyond the veil of the mortal world lies a realm of pure possibility and absolute terror. Stars are born and die here in moments, and the beings that call this place home have never known mortality.",
+    emoji: "🌌",
+    status: "locked",
+    unlockBossId: "void_titan",
+  },
 ];