feat(adapters): 接入 CloudCone/Zeabur/Dynadot/新网/Agnes 五个平台

线上平台列表里 cloudcone、zeabur、xinwang、dynadot、agnes 的 sdk_type 仍为空，
平台卡片只能显示「未对接」，用户无法同步。按各自真实 API 能力补齐：

- CloudCone：实例清单 + 开机/关机/重启；无公开账单接口，不声明余额与续费
- Zeabur：服务器清单 + 重启；毫核/MB 归一化为核/GB，未采集时不伪造规格
- Dynadot：域名清单（含到期日）+ 账户余额；set_dns2 位置参数无法安全 CRUD
- 新网：代理 API 按域名逐个查到期日；无列表接口，需在账号里填 domains 清单
- Agnes：/models 校验 Key；无余额接口，如实标记不支持

配套改动：
- _align_preset_providers 为库中为空的 sdk_type 回填种子值（启动即生效），
  避免新适配器上线后线上仍停留在「未对接」
- 适配器可声明 plain_config，代理号/域名等非密钥字段前端按明文输入
- PRESET_PROVIDERS 五条记录填上对应 sdk_type

测试：445 passed（新增 tests/test_platform_adapters.py），vitest 62 passed。

app/adapters/dynadot.py

@@ -0,0 +1,127 @@
+"""Dynadot 适配器（Domain API v3，API Key 查询参数）
+
+API 文档：https://www.dynadot.com/domain/api-commands
+所需配置：{"api_key": "..."}
+
+覆盖：注册域名清单（含到期日）、账户余额。
+Dynadot 的 DNS 记录通过 set_dns2 的 main_record0..19 位置参数写入，
+无法安全地做「按记录增删改」，故不声明 DNS 能力。
+"""
+
+from datetime import date, datetime, timezone
+
+import httpx
+
+from app.adapters.base import (
+    AccountInfo,
+    BaseAdapter,
+    NormalizedDomain,
+    parse_iso_date,
+)
+from app.adapters.registry import register
+
+
+def _epoch_ms_to_date(value) -> date | None:
+    """Dynadot 的 Expiration 是 Unix 毫秒字符串；兼容秒级和 ISO 字符串"""
+    if value in (None, ""):
+        return None
+    text = str(value).strip()
+    try:
+        num = int(float(text))
+    except ValueError:
+        return parse_iso_date(text)
+    if num > 10_000_000_000:  # 毫秒
+        num //= 1000
+    try:
+        return datetime.fromtimestamp(num, tz=timezone.utc).date()
+    except (ValueError, OSError, OverflowError):
+        return None
+
+
+def _as_list(value) -> list:
+    if isinstance(value, list):
+        return value
+    if isinstance(value, dict):
+        return [value]
+    return []
+
+
+@register("dynadot-api")
+class DynadotAdapter(BaseAdapter):
+    required_config = ["api_key"]
+    BASE = "https://api.dynadot.com/api3.json"
+
+    def _call(self, command: str, params: dict | None = None) -> dict:
+        query = {"key": self.config.get("api_key", ""), "command": command}
+        if params:
+            query.update({k: v for k, v in params.items() if v is not None})
+        with httpx.Client(timeout=30) as client:
+            resp = client.get(self.BASE, params=query)
+            resp.raise_for_status()
+            data = resp.json()
+
+        # 每个命令的根键不同（ListDomainInfoResponse / GetAccountBalanceResponse…）
+        root = next(
+            (v for k, v in data.items() if isinstance(v, dict) and k.endswith("Response")),
+            data if isinstance(data, dict) else {},
+        )
+        code = root.get("ResponseCode", root.get("SuccessCode"))
+        status_text = str(root.get("Status") or "").lower()
+        if str(code) != "0" or status_text == "error":
+            reason = root.get("Error") or root.get("Message") or root.get("Status") or "未知错误"
+            raise RuntimeError(f"Dynadot {command} 失败（code={code}）：{reason}")
+        return root
+
+    def test_connection(self) -> dict:
+        try:
+            acc = self.get_account()
+            if acc.balance is None:
+                return {"ok": True, "message": "连接成功（账户未返回余额）"}
+            return {"ok": True, "message": f"连接成功，账户余额 {acc.balance} {acc.currency}"}
+        except httpx.HTTPStatusError as e:
+            return {"ok": False, "message": f"HTTP {e.response.status_code}：API Key 无效"}
+        except Exception as e:  # noqa: BLE001
+            return {"ok": False, "message": str(e)}
+
+    # ---------------- 只读清单 ----------------
+
+    def list_domains(self) -> list:
+        root = self._call("list_domain")
+        result = []
+        for entry in _as_list(root.get("MainDomains")):
+            # JSON 里可能是 {"Domain": {...}}，也可能直接把字段摊平
+            node = entry.get("Domain") if isinstance(entry.get("Domain"), dict) else entry
+            name = node.get("Name") or entry.get("Name")
+            if not name:
+                continue
+            expiry = _epoch_ms_to_date(node.get("Expiration") or entry.get("Expiration"))
+            status = str(node.get("Status") or entry.get("Status") or "active").lower()
+            result.append(
+                NormalizedDomain(
+                    external_id=str(name),
+                    domain_name=str(name),
+                    registrar="dynadot",
+                    expiry_date=expiry,
+                    status=status,
+                    raw=entry,
+                )
+            )
+        return result
+
+    def get_account(self) -> AccountInfo:
+        root = self._call("get_account_balance")
+        balances = _as_list(root.get("BalanceList"))
+        chosen = next(
+            (b for b in balances if str(b.get("Currency", "")).upper() == "USD"),
+            balances[0] if balances else {},
+        )
+        amount = chosen.get("Amount")
+        try:
+            balance = float(str(amount).replace(",", "")) if amount not in (None, "") else None
+        except (TypeError, ValueError):
+            balance = None
+        return AccountInfo(
+            balance=balance,
+            currency=str(chosen.get("Currency") or "USD").upper(),
+            raw=root,
+        )