refactor: 重构代码架构并使用 Modern Go 特性

- 重命名模块 jwts -> schedule_converter
- 新增 service 包，统一业务逻辑层
- 新增 pkg/logger 包，使用 slog 结构化日志
- 新增 pkg/errors 包，统一错误处理
- 拆分 captcha 包，图片识别移至 service/recognizer
- 清理 models 包，只保留数据结构定义
- 消除 grpc/handler.go 中的重复代码
- 简化 main.go，使用 slog 和 context
- 配置支持单例模式和结构化配置
- 使用 any 替代 interface{}
- 使用 sync.Map 替代 map + RWMutex

service/schedule.go

@@ -0,0 +1,124 @@
+package service
+
+import (
+	"context"
+	"log/slog"
+	"net/http"
+	"time"
+
+	"schedule_converter/auth"
+	"schedule_converter/captcha"
+	"schedule_converter/client"
+	"schedule_converter/config"
+	"schedule_converter/models"
+	"schedule_converter/parser"
+	apperr "schedule_converter/pkg/errors"
+)
+
+type ScheduleService struct {
+	httpClient *http.Client
+	maxRetries int
+	retryDelay time.Duration
+}
+
+type ScheduleOption func(*ScheduleService)
+
+func WithMaxRetries(n int) ScheduleOption {
+	return func(s *ScheduleService) {
+		s.maxRetries = n
+	}
+}
+
+func WithRetryDelay(d time.Duration) ScheduleOption {
+	return func(s *ScheduleService) {
+		s.retryDelay = d
+	}
+}
+
+func NewScheduleService(opts ...ScheduleOption) *ScheduleService {
+	s := &ScheduleService{
+		httpClient: client.Client,
+		maxRetries: 3,
+		retryDelay: 3 * time.Second,
+	}
+	for _, opt := range opts {
+		opt(s)
+	}
+	return s
+}
+
+func NewScheduleServiceWithClient(httpClient *http.Client, opts ...ScheduleOption) *ScheduleService {
+	s := &ScheduleService{
+		httpClient: httpClient,
+		maxRetries: 3,
+		retryDelay: 3 * time.Second,
+	}
+	for _, opt := range opts {
+		opt(s)
+	}
+	return s
+}
+
+func (s *ScheduleService) FetchSchedule(ctx context.Context, username, password, semester string) ([]models.Course, error) {
+	log := slog.With("username", username, "semester", semester)
+
+	if err := client.GetInitialCookiesWithClient(s.httpClient); err != nil {
+		return nil, apperr.New("fetch_schedule", err, "获取Cookie失败")
+	}
+
+	var lastErr error
+	for attempt := 1; attempt <= s.maxRetries; attempt++ {
+		select {
+		case <-ctx.Done():
+			return nil, ctx.Err()
+		default:
+		}
+
+		log.Info("尝试登录", "attempt", attempt, "max_retries", s.maxRetries)
+
+		captchaCode, err := captcha.GetAndRecognize(s.httpClient)
+		if err != nil {
+			log.Warn("验证码获取失败", "error", err, "attempt", attempt)
+			lastErr = err
+			time.Sleep(s.retryDelay)
+			continue
+		}
+
+		success, err := auth.LoginWithClient(s.httpClient, captchaCode, username, password)
+		if err != nil {
+			log.Warn("登录失败", "error", err, "attempt", attempt)
+			lastErr = err
+			time.Sleep(s.retryDelay)
+			continue
+		}
+
+		if success {
+			if semester == "" {
+				semester = config.Semester
+			}
+			courses, err := parser.FetchScheduleWithClient(s.httpClient, semester)
+			if err != nil {
+				return nil, apperr.New("fetch_schedule", err, "获取课表失败")
+			}
+			log.Info("获取课表成功", "course_count", len(courses))
+			return courses, nil
+		}
+
+		log.Warn("登录验证失败，稍后重试", "attempt", attempt)
+		time.Sleep(s.retryDelay)
+	}
+
+	return nil, apperr.New("fetch_schedule", lastErr, "登录失败，已重试")
+}
+
+func (s *ScheduleService) FetchDefaultSchedule(ctx context.Context) ([]models.Course, error) {
+	return s.FetchSchedule(ctx, config.Username, config.Password, config.Semester)
+}
+
+func (s *ScheduleService) FetchScheduleForUser(username, password, semester string) ([]models.Course, error) {
+	return s.FetchSchedule(context.Background(), username, password, semester)
+}
+
+func (s *ScheduleService) FetchDefaultScheduleLegacy() ([]models.Course, error) {
+	return s.FetchScheduleForUser(config.Username, config.Password, config.Semester)
+}