feat: 集成 AI-Core gRPC 文档解析服务

- 新增 AICoreClient 客户端
- 添加 document_parser_client.go
- 知识库服务集成 AI-Core 解析
- 配置中添加 ai_core_service_addr

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

server/internal/service/document_parser_client.go

@@ -0,0 +1,132 @@
+package service
+
+import (
+	"context"
+	"fmt"
+	"time"
+
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/credentials/insecure"
+)
+
+// AICoreClient AI-Core 文档解析服务客户端
+type AICoreClient struct {
+	conn    *grpc.ClientConn
+	address string
+}
+
+// ParseResult 解析结果
+type ParseResult struct {
+	Success       bool
+	Content       string
+	Message       string
+	ContentLength int32
+	FileType      string
+	ParserEngine  string
+}
+
+// NewAICoreClient 创建 AI-Core 客户端
+func NewAICoreClient(address string) (*AICoreClient, error) {
+	return &AICoreClient{address: address}, nil
+}
+
+// Connect 连接到 gRPC 服务
+func (c *AICoreClient) Connect() error {
+	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
+	defer cancel()
+
+	conn, err := grpc.DialContext(ctx, c.address,
+		grpc.WithTransportCredentials(insecure.NewCredentials()),
+		grpc.WithBlock(),
+	)
+	if err != nil {
+		return fmt.Errorf("failed to connect to AI-Core service: %w", err)
+	}
+	c.conn = conn
+	return nil
+}
+
+// Close 关闭连接
+func (c *AICoreClient) Close() {
+	if c.conn != nil {
+		c.conn.Close()
+	}
+}
+
+// ParseDocument 解析文档
+func (c *AICoreClient) ParseDocument(fileURL, fileName, fileType string) (*ParseResult, error) {
+	if c.conn == nil {
+		if err := c.Connect(); err != nil {
+			return nil, err
+		}
+	}
+
+	// 使用 gRPC raw bytes 调用
+	// 由于没有生成 protobuf 代码，使用 raw bytes 方式调用
+	client := NewDocumentParserClient(c.conn)
+
+	req := &ParseRequest{
+		FileUrl:  fileURL,
+		FileName: fileName,
+		FileType: fileType,
+	}
+
+	ctx, cancel := context.WithTimeout(context.Background(), 60*time.Second)
+	defer cancel()
+
+	resp, err := client.ParseDocument(ctx, req)
+	if err != nil {
+		return nil, fmt.Errorf("failed to parse document: %w", err)
+	}
+
+	return &ParseResult{
+		Success:       resp.Success,
+		Content:       resp.Content,
+		Message:       resp.Message,
+		ContentLength: resp.ContentLength,
+		FileType:      resp.FileType,
+		ParserEngine:  resp.ParserEngine,
+	}, nil
+}
+
+// 以下是手动定义的 protobuf messages（与 proto 文件一致）
+// 不需要生成 .pb.go 文件，直接手动定义
+
+type ParseRequest struct {
+	FileUrl       string
+	FileName     string
+	FileType     string
+	ParserEngine string
+}
+
+type ParseResponse struct {
+	Success       bool
+	Content       string
+	Message       string
+	ContentLength int32
+	FileType      string
+	ParserEngine  string
+}
+
+// DocumentParserClient gRPC 客户端接口（手动实现）
+type DocumentParserClient interface {
+	ParseDocument(ctx context.Context, in *ParseRequest, opts ...grpc.CallOption) (*ParseResponse, error)
+}
+
+type documentParserClient struct {
+	cc grpc.ClientConnInterface
+}
+
+// NewDocumentParserClient 创建 DocumentParser 客户端
+func NewDocumentParserClient(cc grpc.ClientConnInterface) DocumentParserClient {
+	return &documentParserClient{cc: cc}
+}
+
+func (c *documentParserClient) ParseDocument(ctx context.Context, in *ParseRequest, opts ...grpc.CallOption) (*ParseResponse, error) {
+	out := new(ParseResponse)
+	err := c.cc.Invoke(ctx, "/docparser.DocumentParser/ParseDocument", in, out, opts...)
+	if err != nil {
+		return nil, err
+	}
+	return out, nil
+}