fix: unify backend port to 18080 and make validator targets configurable

- Set default API port to 18080 in config.py
- Add configurable validation_targets to SettingsSchema and DEFAULT_SETTINGS
- Update ValidatorService to support runtime test URL updates
- Hot-reload validation_targets from DB on startup and on settings save
- Add domestic fallback URLs (baidu.com, qq.com) to reduce foreign dependency risk
- Update Settings.vue to allow adding/removing validator target URLs in UI

app/core/config.py

@@ -16,7 +16,7 @@ class Settings(BaseSettings):
 
     # API 服务配置
     host: str = "127.0.0.1"
-    port: int = 9949
+    port: int = 18080
 
     # 验证器配置
     validator_timeout: int = 5
@@ -40,6 +40,16 @@ class Settings(BaseSettings):
     score_min: int = 0
     score_max: int = 100
 
+    # 验证目标配置
+    validator_test_urls: List[str] = [
+        "http://httpbin.org/ip",
+        "https://httpbin.org/ip",
+        "http://api.ipify.org",
+        "https://api.ipify.org",
+        "http://www.baidu.com",
+        "http://www.qq.com",
+    ]
+
     # 插件配置
     plugins_dir: str = "plugins"