refactor: 移除 Python 后端源码，全面迁移至 Rust gateway 架构

- 删除全部 Python 源码 (src/) 及 Alembic 迁移脚本，归档至 _deprecated_py_src/
- 重构 Rust gateway ai_pipeline: 拆分 planner/finalize 模块，新增 contracts/adaptation 层
- 重组 handlers 模块为 admin/public/proxy/internal/shared 子模块结构
- 新增 executor 模块，引入 Rust 原生数据库迁移 (aether-data/migrations)
- 简化 CI/Docker 构建流程，移除 base image 二级构建，统一为单一 app image
- 移除 Python 相关基础设施文件 (entrypoint.sh, gunicorn_conf.py, Dockerfile.base)

_deprecated_py_src/services/payment/gateway/__init__.py

@@ -0,0 +1,23 @@
+from __future__ import annotations
+
+from src.services.payment.gateway.alipay import AlipayGateway
+from src.services.payment.gateway.base import PaymentGateway
+from src.services.payment.gateway.manual import ManualGateway
+from src.services.payment.gateway.wechat import WeChatGateway
+
+_GATEWAYS: dict[str, PaymentGateway] = {
+    "alipay": AlipayGateway(),
+    "wechat": WeChatGateway(),
+    "manual": ManualGateway(),
+}
+
+
+def get_payment_gateway(payment_method: str) -> PaymentGateway:
+    key = (payment_method or "").strip().lower()
+    gateway = _GATEWAYS.get(key)
+    if gateway is None:
+        raise ValueError(f"unsupported payment_method: {payment_method}")
+    return gateway
+
+
+__all__ = ["PaymentGateway", "get_payment_gateway"]

_deprecated_py_src/services/payment/gateway/alipay.py

@@ -0,0 +1,21 @@
+from __future__ import annotations
+
+from typing import Any
+
+from src.services.payment.gateway.base import PaymentGateway
+
+
+class AlipayGateway(PaymentGateway):
+    payment_method = "alipay"
+    display_name = "支付宝"
+
+    def create_checkout_payload(self, *, order: Any) -> dict[str, Any]:
+        gateway_order_id = getattr(order, "gateway_order_id", None) or f"ali_{order.order_no}"
+        return {
+            "gateway": self.payment_method,
+            "display_name": self.display_name,
+            "gateway_order_id": gateway_order_id,
+            "payment_url": f"/pay/mock/alipay/{order.order_no}",
+            "qr_code": f"mock://alipay/{order.order_no}",
+            "expires_at": getattr(order, "expires_at", None),
+        }

_deprecated_py_src/services/payment/gateway/base.py

@@ -0,0 +1,69 @@
+from __future__ import annotations
+
+import hashlib
+import hmac
+import json
+from abc import ABC, abstractmethod
+from typing import Any
+
+
+class PaymentGateway(ABC):
+    """支付网关抽象。
+
+    当前阶段只提供统一结构和占位返回，便于后续接入真实 SDK。
+    """
+
+    payment_method: str
+    display_name: str
+
+    @abstractmethod
+    def create_checkout_payload(self, *, order: Any) -> dict[str, Any]:
+        """为前端返回统一的支付指引结构。"""
+
+    @staticmethod
+    def build_callback_signature(
+        *,
+        payload: dict[str, Any] | None,
+        callback_secret: str | None,
+    ) -> str | None:
+        if payload is None:
+            return None
+        if not callback_secret:
+            return None
+        canonical = json.dumps(
+            payload,
+            sort_keys=True,
+            ensure_ascii=False,
+            separators=(",", ":"),
+            default=str,
+        )
+        return hmac.new(
+            callback_secret.encode("utf-8"),
+            canonical.encode("utf-8"),
+            hashlib.sha256,
+        ).hexdigest()
+
+    def verify_callback_payload(
+        self,
+        *,
+        payload: dict[str, Any] | None,
+        callback_signature: str | None = None,
+        callback_secret: str | None = None,
+    ) -> bool:
+        """校验回调。
+
+        默认使用 HMAC-SHA256 对 payload 进行签名校验。
+        真实接入时可由各支付渠道覆写该方法使用官方 SDK 验签。
+        """
+        expected_signature = self.build_callback_signature(
+            payload=payload,
+            callback_secret=callback_secret,
+        )
+        if expected_signature is None:
+            return False
+        provided = (callback_signature or "").strip()
+        if not provided:
+            return False
+        if provided.lower().startswith("sha256="):
+            provided = provided.split("=", 1)[1]
+        return hmac.compare_digest(provided.lower(), expected_signature.lower())

_deprecated_py_src/services/payment/gateway/manual.py

@@ -0,0 +1,22 @@
+from __future__ import annotations
+
+from typing import Any
+
+from src.services.payment.gateway.base import PaymentGateway
+
+
+class ManualGateway(PaymentGateway):
+    payment_method = "manual"
+    display_name = "人工打款"
+
+    def create_checkout_payload(self, *, order: Any) -> dict[str, Any]:
+        gateway_order_id = getattr(order, "gateway_order_id", None) or f"manual_{order.order_no}"
+        return {
+            "gateway": self.payment_method,
+            "display_name": self.display_name,
+            "gateway_order_id": gateway_order_id,
+            "payment_url": None,
+            "qr_code": None,
+            "instructions": "请线下确认到账后由管理员处理",
+            "expires_at": getattr(order, "expires_at", None),
+        }

_deprecated_py_src/services/payment/gateway/wechat.py

@@ -0,0 +1,21 @@
+from __future__ import annotations
+
+from typing import Any
+
+from src.services.payment.gateway.base import PaymentGateway
+
+
+class WeChatGateway(PaymentGateway):
+    payment_method = "wechat"
+    display_name = "微信支付"
+
+    def create_checkout_payload(self, *, order: Any) -> dict[str, Any]:
+        gateway_order_id = getattr(order, "gateway_order_id", None) or f"wx_{order.order_no}"
+        return {
+            "gateway": self.payment_method,
+            "display_name": self.display_name,
+            "gateway_order_id": gateway_order_id,
+            "payment_url": f"/pay/mock/wechat/{order.order_no}",
+            "qr_code": f"mock://wechat/{order.order_no}",
+            "expires_at": getattr(order, "expires_at", None),
+        }