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/admin/stats/performance.py

@@ -0,0 +1,93 @@
+"""Admin performance stats routes."""
+
+from __future__ import annotations
+
+from datetime import date, timezone
+from typing import Any
+
+from fastapi import APIRouter, Depends, Query, Request
+from sqlalchemy.orm import Session
+
+from src.api.base.admin_adapter import AdminApiAdapter
+from src.api.base.context import ApiRequestContext
+from src.config.constants import CacheTTL
+from src.database import get_db
+from src.models.database import StatsDaily
+from src.services.system.stats_aggregator import StatsAggregatorService
+from src.services.system.time_range import TimeRangeParams
+from src.utils.cache_decorator import cache_result
+
+from .common import _apply_admin_default_range, _build_time_range_params, pipeline
+
+router = APIRouter()
+
+
+class AdminPercentilesAdapter(AdminApiAdapter):
+    def __init__(self, time_range: TimeRangeParams | None) -> None:
+        self.time_range = _apply_admin_default_range(time_range)
+
+    @cache_result(
+        key_prefix="admin:stats:performance:percentiles",
+        ttl=CacheTTL.ADMIN_USAGE_AGGREGATION,
+        user_specific=False,
+        vary_by=[
+            "time_range.start_date",
+            "time_range.end_date",
+            "time_range.preset",
+            "time_range.timezone",
+            "time_range.tz_offset_minutes",
+        ],
+    )
+    async def handle(self, context: ApiRequestContext) -> Any:  # type: ignore[override]
+        if not self.time_range:
+            return []
+
+        time_range = self.time_range
+        is_utc = (time_range.timezone in {None, "UTC"}) and time_range.tz_offset_minutes == 0
+
+        if is_utc:
+            start_utc, end_utc = time_range.to_utc_datetime_range()
+            rows = (
+                context.db.query(StatsDaily)
+                .filter(StatsDaily.date >= start_utc, StatsDaily.date < end_utc)
+                .order_by(StatsDaily.date.asc())
+                .all()
+            )
+            result = []
+            for row in rows:
+                date_str = (
+                    row.date.astimezone(timezone.utc).date().isoformat()
+                    if row.date.tzinfo
+                    else row.date.date().isoformat()
+                )
+                result.append(
+                    {
+                        "date": date_str,
+                        "p50_response_time_ms": row.p50_response_time_ms,
+                        "p90_response_time_ms": row.p90_response_time_ms,
+                        "p99_response_time_ms": row.p99_response_time_ms,
+                        "p50_first_byte_time_ms": row.p50_first_byte_time_ms,
+                        "p90_first_byte_time_ms": row.p90_first_byte_time_ms,
+                        "p99_first_byte_time_ms": row.p99_first_byte_time_ms,
+                    }
+                )
+            return result
+
+        return StatsAggregatorService.compute_percentiles_by_local_day(context.db, time_range)
+
+
+@router.get("/performance/percentiles")
+async def get_percentiles(
+    request: Request,
+    db: Session = Depends(get_db),
+    start_date: date | None = Query(None),
+    end_date: date | None = Query(None),
+    preset: str | None = Query(None),
+    timezone_name: str | None = Query(None, alias="timezone"),
+    tz_offset_minutes: int | None = Query(0),
+) -> Any:
+    time_range = _build_time_range_params(
+        start_date, end_date, preset, timezone_name, tz_offset_minutes
+    )
+    adapter = AdminPercentilesAdapter(time_range=time_range)
+    return await pipeline.run(adapter=adapter, http_request=request, db=db, mode=adapter.mode)