refactor: query_weather bash→Rust builtin, 删除旧 skill

QWeather 天气查询从外部 bash 脚本重构为 Rust 原生 builtin 工具:
- ed25519-dalek 替代 openssl JWT 签名
- reqwest + tokio::join! 并发查询替代串行 curl
- serde_json 直接解析替代 python3 子进程
- city_id 内存缓存 (HashMap, 1h TTL)
- 支持 3/7/10/15/30d 逐日 + 24/72/168h 逐时预报
- 删除 resources/skills/query_weather/ (builtin 优先级更高)

src/tools/builtin.rs

@@ -9,6 +9,11 @@ impl BuiltinRegistry {
         match name {
             "get_current_datetime" => Some(execute_datetime()),
             "manage_memos" => Some(handle_memos(args_json).await),
+            "query_weather" => {
+                let params: serde_json::Value =
+                    serde_json::from_str(args_json).unwrap_or_default();
+                Some(super::weather::execute(params).await)
+            }
             _ => None,
         }
     }
@@ -30,6 +35,7 @@ impl BuiltinRegistry {
                 parameters: serde_json::json!({"type":"object","properties":{"action":{"type":"string","enum":["add","list","delete"]},"content":{"type":"string"},"id":{"type":"integer"}}}),
                 timeout_secs: 10,
             },
+            super::weather::spec(),
         ]
     }