feat: sequential zone unlocking with dual boss+quest gate conditions

Zones now unlock in strict linear order. Each zone requires both the
final boss AND the final quest of the previous zone to be completed:

Verdant Vale → Shattered Ruins (forest_giant + ancient_ruins)
Shattered Ruins → Frozen Peaks (elder_dragon + dragon_lair)
Frozen Peaks → Shadow Marshes (void_titan + storm_citadel)
Shadow Marshes → Volcanic Depths (mud_kraken + plague_ruins)
Volcanic Depths → Astral Void (phoenix_lord + the_forge)

- Zone type gains `unlockQuestId` field alongside `unlockBossId`
- boss.ts checks both conditions before unlocking zone on boss defeat
- tick.ts checks both conditions and unlocks zones + first boss on
  quest completion if the boss condition is already met
- GameContext optimistic update also respects dual-condition logic
- BossPanel zone-gate hints now show both "⚔️ Defeat: X & 📜 Complete: Y"
- game.ts backfill syncs unlockQuestId and re-verifies zone status
  using both conditions, reverting incorrectly-unlocked saves

apps/web/src/engine/tick.ts

@@ -136,18 +136,57 @@ export const applyTick = (state: GameState, deltaSeconds: number): GameState =>
     return { ...quest, status: "completed" as const };
   });
 
-  // Unlock quests whose prerequisites are now all completed
+  // Unlock quests whose prerequisites are now all completed and whose zone is unlocked
   const completedIds = new Set(
     updatedQuests.filter((q) => q.status === "completed").map((q) => q.id),
   );
   const fullyUpdatedQuests = updatedQuests.map((quest) => {
     if (quest.status !== "locked") return quest;
+    const zone = state.zones.find((z) => z.id === quest.zoneId);
+    if (zone?.status === "locked") return quest;
     if (quest.prerequisiteIds.every((id) => completedIds.has(id))) {
       return { ...quest, status: "available" as const };
     }
     return quest;
   });
 
+  // Unlock zones whose both conditions are now satisfied after quest completion:
+  // (1) the gate boss has been defeated, (2) the gate quest is now completed
+  const updatedZones = state.zones.map((zone) => {
+    if (zone.status === "unlocked") return zone;
+    const bossOk =
+      zone.unlockBossId == null ||
+      state.bosses.some((b) => b.id === zone.unlockBossId && b.status === "defeated");
+    const questOk =
+      zone.unlockQuestId == null || completedIds.has(zone.unlockQuestId);
+    if (bossOk && questOk) {
+      return { ...zone, status: "unlocked" as const };
+    }
+    return zone;
+  });
+
+  // Activate the first boss in any zone that just became unlocked this tick
+  const newlyUnlockedZoneIds = new Set(
+    updatedZones
+      .filter((z) => {
+        const wasLocked = state.zones.find((oz) => oz.id === z.id)?.status === "locked";
+        return z.status === "unlocked" && wasLocked;
+      })
+      .map((z) => z.id),
+  );
+  let updatedBosses = state.bosses;
+  if (newlyUnlockedZoneIds.size > 0) {
+    updatedBosses = state.bosses.map((boss) => {
+      if (!newlyUnlockedZoneIds.has(boss.zoneId ?? "")) return boss;
+      const zoneBosses = state.bosses.filter((b) => b.zoneId === boss.zoneId);
+      const firstBoss = zoneBosses[0];
+      if (firstBoss?.id === boss.id && boss.status === "locked") {
+        return { ...boss, status: "available" as const };
+      }
+      return boss;
+    });
+  }
+
   const newGold = state.resources.gold + goldGained + questGold;
   const newEssence = state.resources.essence + essenceGained + questEssence;
   const newTotalGoldEarned = state.player.totalGoldEarned + goldGained + questGold;
@@ -168,6 +207,8 @@ export const applyTick = (state: GameState, deltaSeconds: number): GameState =>
     upgrades: updatedUpgrades,
     adventurers: updatedAdventurers,
     equipment: updatedEquipment,
+    bosses: updatedBosses,
+    zones: updatedZones,
     lastTickAt: now,
   };