修复：升级 Pydantic v2 兼容性，修复插件加载错误

- 更新 danding_points 配置使用 pydantic_settings.BaseSettings 和 SettingsConfigDict
- 更新 onmyoji_gacha 配置使用 pydantic_settings.BaseSettings
- 修复 danding_qqpush 配置加载使用 model_validate 替代 parse_obj
- 添加 group_horse_racing 插件的详细 README 文档

这些修复解决了 Pydantic v2 迁移中的导入错误和 API 变更问题。

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

danding_bot/plugins/danding_points/config.py

@@ -1,26 +1,31 @@
-from pydantic import BaseSettings, validator
+from pydantic import field_validator
+from pydantic_settings import BaseSettings, SettingsConfigDict
 from pathlib import Path
 
 
 class Config(BaseSettings):
     """Points system configuration."""
 
+    model_config = SettingsConfigDict(
+        env_prefix="DANDING_",
+        case_sensitive=True,
+        extra="ignore",
+    )
+
     POINTS_DB_FILE: str = "data/danding_points/points.db"
     POINTS_MAX_BALANCE: int = 0  # 0 = unlimited
     POINTS_MAX_PER_OPERATION: int = 0  # 0 = unlimited
     POINTS_LOG_RETENTION_DAYS: int = 365
 
-    class Config:
-        env_prefix = "DANDING_"
-        case_sensitive = True
-
-    @validator("POINTS_MAX_BALANCE", "POINTS_MAX_PER_OPERATION", "POINTS_LOG_RETENTION_DAYS")
+    @field_validator("POINTS_MAX_BALANCE", "POINTS_MAX_PER_OPERATION", "POINTS_LOG_RETENTION_DAYS")
+    @classmethod
     def validate_non_negative(cls, v):
         if v < 0:
             raise ValueError("Value must be non-negative")
         return v
 
-    @validator("POINTS_DB_FILE")
+    @field_validator("POINTS_DB_FILE")
+    @classmethod
     def validate_db_path(cls, v):
         if not v:
             raise ValueError("Database file path cannot be empty")