feat: P1 full implementation - 8 modules + frontend pages + feishu WS

P1 Backend (8 modules, 50+ new API endpoints):
- P1-1: Stakeholder management (power-interest matrix)
- P1-2: WBS task decomposition (tree structure + AI split)
- P1-3: Risk management (register + matrix + AI identify)
- P1-4: Requirement pool (MoSCoW + coverage + conflict detect)
- P1-5: Change management (submit → evaluate → approve → implement)
- P1-6: Health report (6 dimensions + red/yellow/green)
- P1-7: Retrospective & knowledge base
- P1-8: Multi-model support (6 models + strategy selection)

Frontend (9 pages with sidebar navigation):
- Project wizard, Kanban, Stakeholders, WBS, Risks,
  Requirements, Changes, Health, Retrospective

Feishu integration:
- WebSocket long-connection for receiving messages
- Card button callback with decision tracking
- 11 chat commands for P0+P1 features

Tech: TypeScript, React 18, Arco Design, Hono, @larksuiteoapi/node-sdk

src/pages/KanbanPage.tsx

@@ -0,0 +1,8 @@
+import React from 'react';
+import KanbanBoard from '../components/KanbanBoard';
+
+const KanbanPage: React.FC = () => {
+  return <KanbanBoard />;
+};
+
+export default KanbanPage;