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/request/model_test_debug.py

@@ -0,0 +1,57 @@
+from __future__ import annotations
+
+from copy import deepcopy
+from typing import Any
+
+MODEL_TEST_DEBUG_KEY = "model_test_debug"
+MODEL_TEST_DEBUG_ATTR = "_model_test_debug"
+
+
+def normalize_model_test_debug_payload(debug_payload: Any) -> dict[str, Any] | None:
+    if not isinstance(debug_payload, dict):
+        return None
+
+    normalized: dict[str, Any] = {}
+    for key in (
+        "request_url",
+        "request_headers",
+        "request_body",
+        "response_headers",
+        "response_body",
+    ):
+        value = debug_payload.get(key)
+        if value is None:
+            continue
+        normalized[key] = deepcopy(value)
+
+    return normalized or None
+
+
+def set_candidate_model_test_debug(candidate: Any, debug_payload: Any) -> None:
+    normalized = normalize_model_test_debug_payload(debug_payload)
+    if normalized is None:
+        return
+    setattr(candidate, MODEL_TEST_DEBUG_ATTR, normalized)
+
+
+def get_candidate_model_test_debug(candidate: Any) -> dict[str, Any] | None:
+    return normalize_model_test_debug_payload(getattr(candidate, MODEL_TEST_DEBUG_ATTR, None))
+
+
+def merge_model_test_debug(
+    extra_data: dict[str, Any] | None,
+    debug_payload: Any,
+) -> dict[str, Any] | None:
+    normalized = normalize_model_test_debug_payload(debug_payload)
+    if normalized is None:
+        return extra_data
+
+    merged = dict(extra_data or {})
+    merged[MODEL_TEST_DEBUG_KEY] = normalized
+    return merged
+
+
+def get_model_test_debug_from_extra_data(extra_data: Any) -> dict[str, Any] | None:
+    if not isinstance(extra_data, dict):
+        return None
+    return normalize_model_test_debug_payload(extra_data.get(MODEL_TEST_DEBUG_KEY))