feat(iit): QC deep fix + V3.1 architecture plan + project member management

QC System Deep Fix:
- HardRuleEngine: add null tolerance + field availability pre-check (skipped status)
- SkillRunner: baseline data merge for follow-up events + field availability check
- QcReportService: record-level pass rate calculation + accurate LLM XML report
- iitBatchController: legacy log cleanup (eventId=null) + upsert RecordSummary
- seed-iit-qc-rules: null/empty string tolerance + applicableEvents config

V3.1 Architecture Design (docs only, no code changes):
- QC engine V3.1 plan: 5-level data structure (CDISC ODM) + D1-D7 dimensions
- Three-batch implementation strategy (A: foundation, B: bubbling, C: new engines)
- Architecture team review: 4 whitepapers reviewed + feedback doc + 4 critical suggestions
- CRA Agent strategy roadmap + CRA 4-tool explanation doc for clinical experts

Project Member Management:
- Cross-tenant member search and assignment (remove tenant restriction)
- IIT project detail page enhancement with tabbed layout (KB + members)
- IitProjectContext for business-side project selection
- System-KB route access control adjustment for project operators

Frontend:
- AdminLayout sidebar menu restructure
- IitLayout with project context provider
- IitMemberManagePage new component
- Business-side pages adapt to project context

Prisma:
- 2 new migrations (user-project RBAC + is_demo flag)
- Schema updates for project member management

Made-with: Cursor

docs/05-部署文档/03-待部署变更清单.md

@@ -16,6 +16,7 @@
 | # | 变更内容 | 迁移文件 | 优先级 | 备注 |
 |---|---------|---------|--------|------|
 | DB-1 | ssa_workflows 类型精度对齐 + 清理重复 FK | `20260227_align_schema_with_db_types` | 低 | 幂等 SQL，RDS 上执行无副作用 |
+| DB-2 | Phase 2: user_mappings 加 user_id FK + projects 加 tenant_id FK + UserRole 加 IIT_OPERATOR | `20260228_add_iit_phase2_user_project_rbac` | 高 | nullable 列，不破坏现有数据 |
 
 ### 后端变更 (Node.js)