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/prompt_cache.py

@@ -0,0 +1,175 @@
+"""Helpers for synthesizing stable prompt cache keys."""
+
+from __future__ import annotations
+
+import re
+import uuid
+from collections.abc import Mapping
+from typing import Any
+
+from src.core.provider_types import ProviderType, normalize_provider_type
+from src.utils.url_utils import is_official_openai_api_url
+
+_OFFICIAL_OPENAI_PROMPT_CACHE_FORMATS: frozenset[str] = frozenset({"openai:chat", "openai:cli"})
+_PROMPT_CACHE_NAMESPACE_VERSION = "v3"
+_USER_AGENT_CLIENT_FAMILY_PATTERNS: tuple[tuple[tuple[str, ...], str], ...] = (
+    (("codex desktop",), "codex_desktop"),
+    (("asyncopenai/python", "openai/python"), "openai_python"),
+    (("openai-node", "openai/javascript"), "openai_node"),
+    (("openai-go",), "openai_go"),
+    (("openai-java",), "openai_java"),
+    (("openai-ruby",), "openai_ruby"),
+    (("postmanruntime/",), "postman"),
+    (("curl/",), "curl"),
+    (("mozilla/",), "browser"),
+)
+
+
+def _get_header_value(headers: Mapping[str, Any] | None, header_name: str) -> str | None:
+    if not isinstance(headers, Mapping):
+        return None
+
+    target = str(header_name or "").strip().lower()
+    if not target:
+        return None
+
+    for name, value in headers.items():
+        if str(name or "").strip().lower() != target:
+            continue
+        normalized = str(value or "").strip()
+        return normalized or None
+    return None
+
+
+def normalize_prompt_cache_client_family(user_agent: str | None) -> str:
+    """Reduce a raw User-Agent string to a stable client-family token."""
+    raw = str(user_agent or "").strip().lower()
+    if not raw:
+        return "generic"
+
+    for patterns, family in _USER_AGENT_CLIENT_FAMILY_PATTERNS:
+        if any(pattern in raw for pattern in patterns):
+            return family
+
+    normalized = re.sub(r"[^a-z0-9]+", "_", raw.split()[0].split("/")[0]).strip("_")
+    return normalized[:48] if normalized else "generic"
+
+
+def resolve_prompt_cache_client_family(request_headers: Mapping[str, Any] | None) -> str:
+    """Best-effort client-family extraction from request headers."""
+    return normalize_prompt_cache_client_family(_get_header_value(request_headers, "user-agent"))
+
+
+def _build_stable_prompt_cache_key(
+    user_api_key_id: str | None,
+    *,
+    scope: str,
+    client_family: str | None = None,
+) -> str | None:
+    normalized = str(user_api_key_id or "").strip()
+    if not normalized:
+        return None
+
+    # Keep the optional argument for call-site compatibility, but ignore it.
+    # Prompt cache reuse is more valuable than splitting namespaces by User-Agent.
+    _ = client_family
+    namespace = f"aether:{scope}:prompt-cache:{_PROMPT_CACHE_NAMESPACE_VERSION}:user:{normalized}"
+    return str(uuid.uuid5(uuid.NAMESPACE_OID, namespace))
+
+
+def build_stable_openai_prompt_cache_key(
+    user_api_key_id: str | None,
+    *,
+    client_family: str | None = None,
+) -> str | None:
+    """Build a deterministic official OpenAI prompt cache key from the caller's user API key id."""
+    return _build_stable_prompt_cache_key(
+        user_api_key_id,
+        scope="openai",
+        client_family=client_family,
+    )
+
+
+def build_stable_codex_prompt_cache_key(
+    user_api_key_id: str | None,
+    *,
+    client_family: str | None = None,
+) -> str | None:
+    """Build a deterministic Codex prompt cache key from the caller's user API key id."""
+    return _build_stable_prompt_cache_key(
+        user_api_key_id,
+        scope="codex",
+        client_family=client_family,
+    )
+
+
+def resolve_prompt_cache_key_scope(
+    *,
+    provider_api_format: str | None,
+    provider_type: str | None = None,
+    base_url: str | None = None,
+) -> str | None:
+    """Resolve which prompt cache strategy should be used for this request."""
+    fmt = str(provider_api_format or "").strip().lower()
+    pt = normalize_provider_type(provider_type)
+    if pt == ProviderType.CODEX.value and fmt in {"openai:cli", "openai:compact"}:
+        return "codex"
+
+    if fmt == "openai:compact":
+        return None
+
+    if fmt in _OFFICIAL_OPENAI_PROMPT_CACHE_FORMATS and is_official_openai_api_url(base_url):
+        return "openai"
+
+    return None
+
+
+def maybe_patch_request_with_prompt_cache_key(
+    request_body: Any,
+    *,
+    provider_api_format: str | None,
+    provider_type: str | None = None,
+    base_url: str | None = None,
+    user_api_key_id: str | None = None,
+    request_headers: Mapping[str, Any] | None = None,
+) -> Any:
+    """Inject a stable prompt_cache_key when the target upstream supports deterministic reuse."""
+    if not isinstance(request_body, dict):
+        return request_body
+
+    scope = resolve_prompt_cache_key_scope(
+        provider_api_format=provider_api_format,
+        provider_type=provider_type,
+        base_url=base_url,
+    )
+    if not scope:
+        return request_body
+
+    prompt_cache_key = str(request_body.get("prompt_cache_key") or "").strip()
+    if prompt_cache_key:
+        return request_body
+
+    if scope == "codex":
+        stable_key = build_stable_codex_prompt_cache_key(
+            user_api_key_id,
+        )
+    else:
+        stable_key = build_stable_openai_prompt_cache_key(
+            user_api_key_id,
+        )
+    if not stable_key:
+        return request_body
+
+    out = dict(request_body)
+    out["prompt_cache_key"] = stable_key
+    return out
+
+
+__all__ = [
+    "build_stable_codex_prompt_cache_key",
+    "build_stable_openai_prompt_cache_key",
+    "maybe_patch_request_with_prompt_cache_key",
+    "normalize_prompt_cache_client_family",
+    "resolve_prompt_cache_client_family",
+    "resolve_prompt_cache_key_scope",
+]