refactor: remove region_names dict, use regions traversal instead (#40)

The region_names dictionary was a redundant index that needed manual
sync when HistoryManager modified region names. This caused bugs where
resolve_query couldn't find regions by their new (history-modified) names.

Instead of maintaining two data structures (regions[id] and region_names[name]),
we now only use regions[id] as the single source of truth. The _resolve_region
function iterates over regions.values() to find matches by name.

This approach:
- Eliminates the sync bug entirely
- Simplifies the codebase
- Has negligible performance impact (region count is small)

Co-authored-by: Zihao Xu <xzhseh@gmail.com>

src/classes/map.py

@@ -20,18 +20,14 @@ class Map():
         self.region_cors: dict[int, list[tuple[int, int]]] = {}
         
         # 区域字典，由外部加载器 (load_map.py) 填充
+        # 只维护 regions[id] 作为唯一的 source of truth，按名称查找通过遍历实现
         self.regions = {}
-        self.region_names = {}
         self.sect_regions = {}
         
-        # 这些分类字典可能暂时不再自动维护，或者需要 load_map.py 手动维护
-        # 为了兼容性，先初始化为空
+        # 分类字典（暂未使用，保留以备兼容）
         self.normal_regions = {}
-        self.normal_region_names = {}
         self.cultivate_regions = {}
-        self.cultivate_region_names = {}
         self.city_regions = {}
-        self.city_region_names = {}
 
     def update_sect_regions(self) -> None:
         """根据当前 self.regions 动态刷新宗门总部区域字典。"""