fix(production-readiness): 3-batch production readiness cleanup — 12 tasks

Batch 1 — User-facing fixes:
- B1-1: Pipeline verified end-to-end (14 Rust commands, 8 frontend invoke, fully connected)
- B1-2: MessageSearch restored to ChatArea with search button in DeerFlow header
- B1-3: Viking cleanup — removed 5 orphan invokes (no Rust impl), added addWithMetadata + storeWithSummaries methods + summary generation UI
- B1-4: api-fallbacks transparency — added _isFallback markers + console.warn to all 6 fallback functions

Batch 2 — System health:
- B2-1: Document drift calibration — TRUTH.md/README.md numbers verified and updated
- B2-2: @reserved annotations on 15 SaaS handler functions with no frontend callers
- B2-3: Scheduled Task Admin V2 — new service + page + route + sidebar navigation
- B2-4: TRUTH.md Pipeline/Viking/ScheduledTask records corrected

Batch 3 — Long-term quality:
- B3-1: hand_run_status/hand_run_list verified as fully implemented (not stubs)
- B3-2: Identity snapshot rollback UI added to RightPanel
- B3-3: P2 code quality — 4 fixes (TODO comments, fire-and-forget notes, design notes, table name validation), 2 verified N/A, 1 upstream
- B3-4: Config PATCH→PUT alignment (admin-v2 config.ts matched to SaaS backend)

admin-v2/src/layouts/AdminLayout.tsx

@@ -19,6 +19,7 @@ import {
   BookOutlined,
   CrownOutlined,
   SafetyOutlined,
+  FieldTimeOutlined,
 } from '@ant-design/icons'
 import { Avatar, Dropdown, Tooltip, Drawer } from 'antd'
 import { useAuthStore } from '@/stores/authStore'
@@ -46,6 +47,7 @@ const navItems: NavItem[] = [
   { path: '/api-keys', name: 'API 密钥', icon: <ApiOutlined />, permission: 'provider:manage', group: '资源管理' },
   { path: '/usage', name: '用量统计', icon: <BarChartOutlined />, permission: 'admin:full', group: '运维' },
   { path: '/relay', name: '中转任务', icon: <SwapOutlined />, permission: 'relay:use', group: '运维' },
+  { path: '/scheduled-tasks', name: '定时任务', icon: <FieldTimeOutlined />, permission: 'scheduler:read', group: '运维' },
   { path: '/knowledge', name: '知识库', icon: <BookOutlined />, permission: 'knowledge:read', group: '资源管理' },
   { path: '/billing', name: '计费管理', icon: <CrownOutlined />, permission: 'billing:read', group: '核心' },
   { path: '/logs', name: '操作日志', icon: <FileTextOutlined />, permission: 'admin:full', group: '运维' },
@@ -211,6 +213,7 @@ const breadcrumbMap: Record<string, string> = {
   '/agent-templates': 'Agent 模板',
   '/usage': '用量统计',
   '/relay': '中转任务',
+  '/scheduled-tasks': '定时任务',
   '/knowledge': '知识库',
   '/billing': '计费管理',
   '/config': '系统配置',