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.cpp

@@ -0,0 +1,68 @@
+#include "quest_editor.hpp"
+#include "core/logger.hpp"
+#include <fstream>
+#include <filesystem>
+
+namespace wowee {
+namespace editor {
+
+void QuestEditor::addQuest(const Quest& q) {
+    Quest quest = q;
+    quest.id = nextId_++;
+    quests_.push_back(quest);
+    LOG_INFO("Quest added: [", quest.id, "] ", quest.title);
+}
+
+void QuestEditor::removeQuest(int index) {
+    if (index >= 0 && index < static_cast<int>(quests_.size()))
+        quests_.erase(quests_.begin() + index);
+}
+
+Quest* QuestEditor::getQuest(int index) {
+    if (index < 0 || index >= static_cast<int>(quests_.size())) return nullptr;
+    return &quests_[index];
+}
+
+bool QuestEditor::saveToFile(const std::string& path) const {
+    auto dir = std::filesystem::path(path).parent_path();
+    if (!dir.empty()) std::filesystem::create_directories(dir);
+
+    std::ofstream f(path);
+    if (!f) return false;
+
+    f << "[\n";
+    for (size_t i = 0; i < quests_.size(); i++) {
+        const auto& q = quests_[i];
+        f << "  {\n";
+        f << "    \"id\": " << q.id << ",\n";
+        f << "    \"title\": \"" << q.title << "\",\n";
+        f << "    \"description\": \"" << q.description << "\",\n";
+        f << "    \"completionText\": \"" << q.completionText << "\",\n";
+        f << "    \"requiredLevel\": " << q.requiredLevel << ",\n";
+        f << "    \"questGiverNpcId\": " << q.questGiverNpcId << ",\n";
+        f << "    \"turnInNpcId\": " << q.turnInNpcId << ",\n";
+        f << "    \"nextQuestId\": " << q.nextQuestId << ",\n";
+        f << "    \"reward\": {\"xp\":" << q.reward.xp
+          << ",\"gold\":" << q.reward.gold
+          << ",\"silver\":" << q.reward.silver
+          << ",\"copper\":" << q.reward.copper << "},\n";
+        f << "    \"objectives\": [";
+        for (size_t j = 0; j < q.objectives.size(); j++) {
+            const auto& obj = q.objectives[j];
+            f << "{\"type\":" << static_cast<int>(obj.type)
+              << ",\"desc\":\"" << obj.description << "\""
+              << ",\"target\":\"" << obj.targetName << "\""
+              << ",\"count\":" << obj.targetCount << "}";
+            if (j + 1 < q.objectives.size()) f << ",";
+        }
+        f << "]\n";
+        f << "  }" << (i + 1 < quests_.size() ? "," : "") << "\n";
+    }
+    f << "]\n";
+
+    LOG_INFO("Quests saved: ", path, " (", quests_.size(), " quests)");
+    return true;
+}
+
+} // namespace editor
+} // namespace wowee