feat(aia): Integrate PromptService for 10 AI agents

Features:
- Migrate 10 agent prompts from hardcoded to database
- Add grayscale preview support (DRAFT/ACTIVE distribution)
- Implement 3-tier fallback (DB -> Cache -> Hardcoded)
- Add version management and rollback capability

Files changed:
- backend/scripts/migrate-aia-prompts.ts (new migration script)
- backend/src/common/prompt/prompt.fallbacks.ts (add AIA fallbacks)
- backend/src/modules/aia/services/agentService.ts (integrate PromptService)
- backend/src/modules/aia/services/conversationService.ts (pass userId)
- backend/src/modules/aia/types/index.ts (fix AgentStage type)

Documentation:
- docs/03-业务模块/AIA-AI智能问答/06-开发记录/2026-01-18-Prompt管理系统集成.md
- docs/02-通用能力层/00-通用能力层清单.md (add FileCard, Prompt management)
- docs/00-系统总体设计/00-系统当前状态与开发指南.md (update to v3.6)

Prompt codes:
- AIA_SCIENTIFIC_QUESTION, AIA_PICO_ANALYSIS, AIA_TOPIC_EVALUATION
- AIA_OUTCOME_DESIGN, AIA_CRF_DESIGN, AIA_SAMPLE_SIZE
- AIA_PROTOCOL_WRITING, AIA_METHODOLOGY_REVIEW
- AIA_PAPER_POLISH, AIA_PAPER_TRANSLATE

Tested: Migration script executed, all 10 prompts inserted successfully

backend/src/modules/aia/controllers/attachmentController.ts

@@ -0,0 +1,92 @@
+/**
+ * AIA 智能问答模块 - 附件控制器
+ * @module aia/controllers/attachmentController
+ * 
+ * API 端点：
+ * - POST /api/v1/aia/conversations/:id/attachments  上传附件
+ */
+
+import type { FastifyRequest, FastifyReply } from 'fastify';
+import { logger } from '../../../common/logging/index.js';
+import * as attachmentService from '../services/attachmentService.js';
+
+/**
+ * 从 JWT Token 获取用户 ID
+ */
+function getUserId(request: FastifyRequest): string {
+  const userId = (request as any).user?.userId;
+  if (!userId) {
+    throw new Error('User not authenticated');
+  }
+  return userId;
+}
+
+/**
+ * 上传附件
+ * POST /api/v1/aia/conversations/:id/attachments
+ */
+export async function uploadAttachment(
+  request: FastifyRequest<{
+    Params: { id: string };
+  }>,
+  reply: FastifyReply
+) {
+  try {
+    const userId = getUserId(request);
+    const { id: conversationId } = request.params;
+
+    // 获取上传的文件
+    const data = await request.file();
+    
+    if (!data) {
+      return reply.status(400).send({
+        code: -1,
+        error: {
+          code: 'VALIDATION_ERROR',
+          message: '请上传文件',
+        },
+      });
+    }
+
+    const buffer = await data.toBuffer();
+
+    logger.info('[AIA:AttachmentController] 上传附件', {
+      userId,
+      conversationId,
+      filename: data.filename,
+      mimetype: data.mimetype,
+      size: buffer.length,
+    });
+
+    const attachment = await attachmentService.uploadAttachment(
+      userId,
+      conversationId,
+      {
+        filename: data.filename,
+        mimetype: data.mimetype,
+        buffer,
+      }
+    );
+
+    return reply.send({
+      code: 0,
+      data: attachment,
+    });
+  } catch (error) {
+    const errorMessage = error instanceof Error ? error.message : String(error);
+    logger.error('[AIA:AttachmentController] 上传附件失败', { 
+      error: errorMessage,
+      stack: error instanceof Error ? error.stack : undefined,
+    });
+    
+    return reply.status(500).send({
+      code: -1,
+      error: {
+        code: 'INTERNAL_ERROR',
+        message: errorMessage,
+      },
+    });
+  }
+}
+
+