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/api/public/openai.py

@@ -0,0 +1,95 @@
+"""
+OpenAI API 端点
+
+- /v1/chat/completions - OpenAI Chat API
+- /v1/responses - OpenAI Responses API (CLI)
+- /v1/responses/compact - OpenAI Responses Compaction API (CLI)
+
+注意: /v1/models 端点由 models.py 统一处理，根据请求头返回对应格式
+"""
+
+from typing import Any
+
+from fastapi import APIRouter, Depends, Request
+from sqlalchemy.orm import Session
+
+from src.api.base.pipeline import get_pipeline
+from src.database import get_db
+
+router = APIRouter(tags=["OpenAI API"])
+pipeline = get_pipeline()
+
+
+async def _run_openai_route_shell(adapter: Any, http_request: Request, db: Session) -> Any:
+    return await pipeline.run(
+        adapter=adapter,
+        http_request=http_request,
+        db=db,
+        mode=adapter.mode,
+    )
+
+
+@router.post("/v1/chat/completions")
+async def create_chat_completion(
+    http_request: Request,
+    db: Session = Depends(get_db),
+) -> Any:
+    """
+    OpenAI Chat Completions API
+
+    兼容 OpenAI Chat Completions API 格式的代理接口。
+
+    **认证方式**: Bearer Token（API Key 或 JWT Token）
+
+    **请求格式**:
+    ```json
+    {
+        "model": "gpt-4",
+        "messages": [{"role": "user", "content": "Hello"}],
+        "stream": false
+    }
+    ```
+
+    **支持的参数**: model, messages, stream, temperature, max_tokens 等标准 OpenAI 参数
+    """
+    from src.api.handlers.openai import OpenAIChatAdapter
+
+    adapter = OpenAIChatAdapter()
+    return await _run_openai_route_shell(adapter, http_request, db)
+
+
+@router.post("/v1/responses/compact")
+async def create_responses_compact(
+    http_request: Request,
+    db: Session = Depends(get_db),
+) -> Any:
+    """
+    OpenAI Responses Compaction API (CLI)
+
+    用于压缩/总结之前的 responses，永远非流式。
+    Codex CLI 使用 compact 模型后缀（如 gpt-5-compact）时调用此端点。
+
+    **认证方式**: Bearer Token（API Key 或 JWT Token）
+    """
+    from src.api.handlers.openai_cli import OpenAICompactAdapter
+
+    adapter = OpenAICompactAdapter()
+    return await _run_openai_route_shell(adapter, http_request, db)
+
+
+@router.post("/v1/responses")
+async def create_responses(
+    http_request: Request,
+    db: Session = Depends(get_db),
+) -> Any:
+    """
+    OpenAI Responses API (CLI)
+
+    兼容 OpenAI Codex CLI 使用的 Responses API 格式，请求透传到上游。
+
+    **认证方式**: Bearer Token（API Key 或 JWT Token）
+    """
+    from src.api.handlers.openai_cli import OpenAICliAdapter
+
+    adapter = OpenAICliAdapter()
+    return await _run_openai_route_shell(adapter, http_request, db)