feat(editor): quest editor with objectives, rewards, and quest chains

- New Quest mode (key 6) with full quest creation panel:
  - Title, description, required level
  - Quest giver / turn-in NPC ID linkage
  - Up to 4 objectives: Kill, Collect, Talk, Explore, Escort, Use Object
  - Rewards: XP and gold
  - Quest chain support via nextQuestId linking
- Quest list showing all created quests with level and objective count
- Save quests to JSON (included in Export Zone package)
- Foundation for campaign system: create quest chains across NPCs,
  link objectives to placed creatures, build storylines

tools/editor/quest_editor.hpp

@@ -0,0 +1,67 @@
+#pragma once
+
+#include <glm/glm.hpp>
+#include <string>
+#include <vector>
+#include <cstdint>
+
+namespace wowee {
+namespace editor {
+
+enum class QuestObjectiveType {
+    KillCreature,
+    CollectItem,
+    TalkToNPC,
+    ExploreArea,
+    EscortNPC,
+    UseObject
+};
+
+struct QuestObjective {
+    QuestObjectiveType type = QuestObjectiveType::KillCreature;
+    std::string description;
+    std::string targetName;
+    uint32_t targetCount = 1;
+};
+
+struct QuestReward {
+    uint32_t xp = 100;
+    uint32_t gold = 0;
+    uint32_t silver = 0;
+    uint32_t copper = 0;
+    std::vector<std::string> itemRewards;
+};
+
+struct Quest {
+    uint32_t id = 0;
+    std::string title = "New Quest";
+    std::string description;
+    std::string completionText;
+    uint32_t requiredLevel = 1;
+    uint32_t questGiverNpcId = 0;
+    uint32_t turnInNpcId = 0;
+    std::vector<QuestObjective> objectives;
+    QuestReward reward;
+    uint32_t nextQuestId = 0; // chain link
+};
+
+class QuestEditor {
+public:
+    void addQuest(const Quest& q);
+    void removeQuest(int index);
+    Quest* getQuest(int index);
+    const std::vector<Quest>& getQuests() const { return quests_; }
+    size_t questCount() const { return quests_.size(); }
+
+    bool saveToFile(const std::string& path) const;
+
+    Quest& getTemplate() { return template_; }
+
+private:
+    std::vector<Quest> quests_;
+    Quest template_;
+    uint32_t nextId_ = 1;
+};
+
+} // namespace editor
+} // namespace wowee