M4b：ai_provider 删除手术①-⑥——神识全面接管模型出口

- ① 后端删除 app/ai_provider/（38 文件，含 anthropic/openai 格式、billing、audio、embedding）、services/ai_provider_admin.py、core/config/model_config.py、tests/ai_provider/（21 文件）
- ② 连带退役 application/agent/（旧 Agent 循环/steer/follow-up/确认注册表）、application/skill_executor.py、app/skills/（python skills 孤儿）、endpoints/audio.py、application/imports.py（ProviderManager 消费方）；settings 端点收敛为生成偏好
- ③ runs.py 修剪：AgentRunRegistry/steer/follow-up/confirmations 端点退役，保留 list/get/events/cancel/stream；safety 确认改为直接落库裁决（pending→approved/denied）
- ④ 前端删除：models 页、ModelGatewayView、gateway.ts、GatewayPanel（玄关）、ModelGatewayPanel/ModelStrategyForm、audio.ts/useVoiceInput、网关类型与 mock；设置页收敛为外观/语言/通知
- ⑤ 配置收敛：config/models|providers|pricing.example.yaml 归档 shenshi/config/；.env.example 删 provider keys/MODEL_ENDPOINT_POOL/MODEL_CONFIG_PATH，收敛 SHENSHI_*
- ⑥ 验收：rg 审计灵台 Provider SDK import 与 ai_provider 引用归零；后端 528 passed（2 个预存失败经 HEAD 复跑验证与本手术无关）、前端 type-check+201 passed、神识 go vet+test、BFF 4 passed

backend/app/api/v1/deps.py

@@ -11,7 +11,6 @@ import hmac
 from fastapi import Depends, HTTPException, Request
 from sqlalchemy.ext.asyncio import AsyncSession
 
-from app.application.agent.confirmation import ConfirmationRegistry
 from app.application.tool_runtime.runtime import ToolRuntime
 from app.core.config import settings
 from app.db.session import get_session
@@ -47,13 +46,6 @@ def get_confirmation_store(request: Request) -> ConfirmationStore:
     return store
 
 
-def get_confirmation_registry(request: Request) -> ConfirmationRegistry:
-    registry: ConfirmationRegistry = getattr(request.app.state, "confirmation_registry", None)
-    if registry is None:
-        raise _unavailable("确认注册表未就绪")
-    return registry
-
-
 def get_event_store(request: Request) -> EventStore:
     store = getattr(request.app.state, "event_store", None)
     if store is None: