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/provider/adapters/kiro/headers.py

@@ -0,0 +1,102 @@
+"""Kiro header builders."""
+
+from __future__ import annotations
+
+import uuid
+
+from src.services.provider.adapters.kiro.constants import (
+    AWS_EVENTSTREAM_CONTENT_TYPE,
+    AWS_SDK_JS_MAIN_VERSION,
+    AWS_SDK_JS_USAGE_VERSION,
+    CODEWHISPERER_OPTOUT,
+    DEFAULT_KIRO_VERSION,
+    DEFAULT_NODE_VERSION,
+    DEFAULT_SYSTEM_VERSION,
+    KIRO_AGENT_MODE,
+)
+
+
+def build_kiro_ide_tag(*, kiro_version: str, machine_id: str) -> str:
+    version = (kiro_version or DEFAULT_KIRO_VERSION).strip() or DEFAULT_KIRO_VERSION
+    mid = (machine_id or "").strip()
+    return f"KiroIDE-{version}-{mid}" if mid else f"KiroIDE-{version}"
+
+
+def build_x_amz_user_agent_main(*, kiro_version: str, machine_id: str) -> str:
+    return f"aws-sdk-js/{AWS_SDK_JS_MAIN_VERSION} {build_kiro_ide_tag(kiro_version=kiro_version, machine_id=machine_id)}"
+
+
+def build_user_agent_main(
+    *, system_version: str, node_version: str, kiro_version: str, machine_id: str
+) -> str:
+    os_tag = (system_version or DEFAULT_SYSTEM_VERSION).strip() or DEFAULT_SYSTEM_VERSION
+    node_tag = (node_version or DEFAULT_NODE_VERSION).strip() or DEFAULT_NODE_VERSION
+    ide = build_kiro_ide_tag(kiro_version=kiro_version, machine_id=machine_id)
+    return (
+        f"aws-sdk-js/{AWS_SDK_JS_MAIN_VERSION} ua/2.1 os/{os_tag} lang/js "
+        f"md/nodejs#{node_tag} api/codewhispererstreaming#{AWS_SDK_JS_MAIN_VERSION} m/E {ide}"
+    )
+
+
+def build_x_amz_user_agent_usage(*, kiro_version: str, machine_id: str) -> str:
+    ide = build_kiro_ide_tag(kiro_version=kiro_version, machine_id=machine_id)
+    return f"aws-sdk-js/{AWS_SDK_JS_USAGE_VERSION} {ide}"
+
+
+def build_user_agent_usage(*, kiro_version: str, machine_id: str) -> str:
+    ide = build_kiro_ide_tag(kiro_version=kiro_version, machine_id=machine_id)
+    os_tag = DEFAULT_SYSTEM_VERSION
+    node_tag = DEFAULT_NODE_VERSION
+    return (
+        f"aws-sdk-js/{AWS_SDK_JS_USAGE_VERSION} ua/2.1 os/{os_tag} lang/js "
+        f"md/nodejs#{node_tag} api/codewhispererruntime#1.0.0 m/N,E {ide}"
+    )
+
+
+def build_generate_assistant_headers(
+    *,
+    host: str,
+    access_token: str | None = None,
+    machine_id: str,
+    kiro_version: str | None = None,
+    system_version: str | None = None,
+    node_version: str | None = None,
+) -> dict[str, str]:
+    version = (kiro_version or DEFAULT_KIRO_VERSION).strip() or DEFAULT_KIRO_VERSION
+    sys_ver = (system_version or DEFAULT_SYSTEM_VERSION).strip() or DEFAULT_SYSTEM_VERSION
+    node_ver = (node_version or DEFAULT_NODE_VERSION).strip() or DEFAULT_NODE_VERSION
+
+    headers: dict[str, str] = {
+        "Content-Type": "application/json",
+        "Accept": AWS_EVENTSTREAM_CONTENT_TYPE,
+        "host": host,
+        "Connection": "close",
+        "x-amzn-codewhisperer-optout": CODEWHISPERER_OPTOUT,
+        "x-amzn-kiro-agent-mode": KIRO_AGENT_MODE,
+        "x-amz-user-agent": build_x_amz_user_agent_main(
+            kiro_version=version, machine_id=machine_id
+        ),
+        "User-Agent": build_user_agent_main(
+            system_version=sys_ver,
+            node_version=node_ver,
+            kiro_version=version,
+            machine_id=machine_id,
+        ),
+        "amz-sdk-invocation-id": str(uuid.uuid4()),
+        "amz-sdk-request": "attempt=1; max=3",
+    }
+
+    if access_token:
+        headers["Authorization"] = f"Bearer {access_token}"
+
+    return headers
+
+
+__all__ = [
+    "build_generate_assistant_headers",
+    "build_kiro_ide_tag",
+    "build_user_agent_main",
+    "build_user_agent_usage",
+    "build_x_amz_user_agent_main",
+    "build_x_amz_user_agent_usage",
+]