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/pool/health_cache.py

@@ -0,0 +1,104 @@
+"""In-process pool health score cache.
+
+This cache avoids recomputing per-key health aggregation on every request.
+It does not replace persistent health storage; source data still comes from
+``ProviderAPIKey.health_by_format`` carried on key objects.
+"""
+
+from __future__ import annotations
+
+import threading
+import time
+from typing import Any
+
+_TTL_SECONDS = 30.0
+_MAX_PROVIDERS = 500  # 最大缓存 provider 数量，防止无界增长
+_LOCK = threading.Lock()
+_CACHE: dict[str, tuple[float, dict[str, float]]] = {}
+
+
+def aggregate_health_score(health_by_format: Any) -> float:
+    """Aggregate health score from ``health_by_format`` (lower-bound strategy)."""
+    if not isinstance(health_by_format, dict) or not health_by_format:
+        return 1.0
+    scores: list[float] = []
+    for item in health_by_format.values():
+        if not isinstance(item, dict):
+            continue
+        try:
+            score = float(item.get("health_score") or 1.0)
+        except (TypeError, ValueError):
+            score = 1.0
+        scores.append(max(0.0, min(score, 1.0)))
+    if not scores:
+        return 1.0
+    return min(scores)
+
+
+def get_health_scores(provider_id: str, keys: list[Any]) -> dict[str, float]:
+    """Return key health scores with per-provider TTL cache.
+
+    Uses incremental merge: if the cache is still valid but missing some keys,
+    only the missing keys are computed and merged into the existing cache entry.
+    """
+    now = time.monotonic()
+    keys_by_id: dict[str, Any] = {}
+    for k in keys:
+        kid = str(getattr(k, "id", "") or "")
+        if kid:
+            keys_by_id[kid] = k
+    if not keys_by_id:
+        return {}
+
+    with _LOCK:
+        cached = _CACHE.get(provider_id)
+        if cached is not None:
+            expires_at, payload = cached
+            if now < expires_at:
+                missing_ids = [kid for kid in keys_by_id if kid not in payload]
+                if not missing_ids:
+                    return {kid: payload[kid] for kid in keys_by_id}
+                # Compute only for missing keys, merge into existing cache
+                for kid in missing_ids:
+                    payload[kid] = aggregate_health_score(
+                        getattr(keys_by_id[kid], "health_by_format", None)
+                    )
+                # Trim stale key entries that are no longer in the current key set
+                stale_ids = [sid for sid in payload if sid not in keys_by_id]
+                for sid in stale_ids:
+                    del payload[sid]
+                return {kid: payload[kid] for kid in keys_by_id}
+
+    fresh: dict[str, float] = {}
+    for kid, key in keys_by_id.items():
+        fresh[kid] = aggregate_health_score(getattr(key, "health_by_format", None))
+
+    with _LOCK:
+        _CACHE[provider_id] = (now + _TTL_SECONDS, fresh)
+        # 超出上限时清理过期条目，仍超限则淘汰最旧条目
+        if len(_CACHE) > _MAX_PROVIDERS:
+            expired = [k for k, (exp, _) in _CACHE.items() if now >= exp]
+            for k in expired:
+                del _CACHE[k]
+            if len(_CACHE) > _MAX_PROVIDERS:
+                oldest_key = min(_CACHE, key=lambda k: _CACHE[k][0])
+                del _CACHE[oldest_key]
+    return dict(fresh)
+
+
+def invalidate_provider_health_scores(provider_id: str) -> None:
+    """Invalidate health-score cache for one provider."""
+    with _LOCK:
+        _CACHE.pop(provider_id, None)
+
+
+def _clear_cache_for_tests() -> None:
+    with _LOCK:
+        _CACHE.clear()
+
+
+__all__ = [
+    "aggregate_health_score",
+    "get_health_scores",
+    "invalidate_provider_health_scores",
+]