refactor(grpc): restructure task handling and migrate to slog

Refactor the gRPC client and task handling logic to improve modularity,
error handling, and observability.

- Split `grpc/handler.go` into specialized handler files (login,
  classroom, exams, grades, schedule) to reduce complexity.
- Replace standard `log` with `log/slog` throughout the project for
  structured logging.
- Refactor `grpc/client.go` to use a thread-safe connection management
  pattern with `sync.RWMutex`.
- Remove the legacy `service` package and HTTP server implementation,
  transitioning the application to a pure gRPC runner mode.
- Clean up `config` and `pkg/errors` to remove unused utilities and
  simplify the API.
- Improve error reporting in parsers and HTTP clients by checking
  response status codes.

parser/schedule.go

@@ -1,11 +1,9 @@
 package parser
 
 import (
-	"encoding/json"
 	"fmt"
 	"io"
 	"net/http"
-	"os"
 	"regexp"
 	"sort"
 	"strconv"
@@ -26,17 +24,11 @@ type weekRoomEntry struct {
 }
 
 // 获取课表
-func FetchSchedule(httpClient *http.Client) ([]models.Course, error) {
-	return FetchScheduleWithClient(httpClient, config.Semester)
-}
-
 // FetchScheduleWithClient 使用指定的 HTTP 客户端和学期获取课表
 func FetchScheduleWithClient(httpClient *http.Client, semester string) ([]models.Course, error) {
-	fmt.Println("[5] 获取课表数据...")
-
 	// POST请求获取课表
 	data := fmt.Sprintf("xnxq=%s", semester)
-	req, err := http.NewRequest("POST", config.BaseURL+"/kbcx/queryGrkb", strings.NewReader(data))
+	req, err := http.NewRequest("POST", config.Get().BaseURL+"/kbcx/queryGrkb", strings.NewReader(data))
 	if err != nil {
 		return nil, err
 	}
@@ -54,35 +46,7 @@ func FetchScheduleWithClient(httpClient *http.Client, semester string) ([]models
 		return nil, err
 	}
 
-	// 解析课表
-	courses, err := ParseScheduleHTML(string(body))
-	if err != nil {
-		return nil, err
-	}
-
-	fmt.Printf("    共提取 %d 门课程\n", len(courses))
-
-	// 输出到JSON
-	jsonData, err := os.Create("schedule_result.json")
-	if err != nil {
-		return nil, err
-	}
-	defer jsonData.Close()
-
-	encoder := json.NewEncoder(jsonData)
-	encoder.SetIndent("", "  ")
-	err = encoder.Encode(courses)
-	if err != nil {
-		return nil, err
-	}
-	fmt.Println("    JSON结果已保存到: schedule_result.json")
-
-	// 打印课程信息
-	for i, course := range courses {
-		fmt.Printf("    课程 %d: %s - %s\n", i+1, course.Name, course.Teacher)
-	}
-
-	return courses, nil
+	return ParseScheduleHTML(string(body))
 }
 
 // 解析课表HTML
@@ -354,27 +318,6 @@ func buildCourseKey(name, teacher, room string) string {
 	return strings.TrimSpace(name) + "|" + strings.TrimSpace(teacher) + "|" + strings.TrimSpace(room)
 }
 
-// extractWeekInfo 提取一段文本中的完整周次片段
-// 例如：于战华[15]周，[2-14]周 -> before=于战华, weeks=[15]周，[2-14]周, after=
-func extractWeekInfo(text string) (beforeWeek, weeksPart, afterWeek string, ok bool) {
-	indexes := weekTokenRegexp.FindAllStringIndex(text, -1)
-	if len(indexes) == 0 {
-		return "", "", "", false
-	}
-
-	firstStart := indexes[0][0]
-	beforeWeek = strings.TrimSpace(text[:firstStart])
-
-	parts := weekTokenRegexp.FindAllString(text, -1)
-	weeksPart = strings.Join(parts, ",")
-
-	// 周次后（含中间）非周次内容作为教室候选
-	tail := strings.TrimSpace(text[firstStart:])
-	afterWeek = strings.TrimSpace(weekTokenRegexp.ReplaceAllString(tail, ""))
-	afterWeek = strings.Trim(afterWeek, "，, ")
-	return beforeWeek, weeksPart, afterWeek, true
-}
-
 // extractWeekEntries 将一段文本拆成多个“周次-地点”片段
 // 例如：李鹏程[2-8]周N楼-335，[9]周N楼-331
 // 会拆成：