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/score.go

@@ -2,6 +2,7 @@ package parser
 
 import (
 	"fmt"
+	"log/slog"
 	"net/http"
 	"strings"
 
@@ -39,16 +40,17 @@ type GPASummary struct {
 	Semesters        string
 }
 
-func FetchGrades(httpClient *http.Client,ExamType ScoreType) ([]GradeEntry, error) {
+func FetchGrades(httpClient *http.Client, examType ScoreType) ([]GradeEntry, error) {
 	var gradeURL string
-	switch ExamType {
+	switch examType {
 	case ScoreTypeMidterm:
-		gradeURL = config.BaseURL + "/cjcx/queryQzcj"
+		gradeURL = config.Get().BaseURL + "/cjcx/queryQzcj"
 	default:
-		gradeURL = config.BaseURL + "/cjcx/queryQmcj"
+		gradeURL = config.Get().BaseURL + "/cjcx/queryQmcj"
 	}
 
-	fmt.Printf("[成绩] 正在获取成绩数据 (%s)...\n", ExamType)
+	log := slog.With("exam_type", string(examType))
+	log.Info("获取成绩数据")
 
 	req, err := http.NewRequest("GET", gradeURL, nil)
 	if err != nil {
@@ -62,23 +64,27 @@ func FetchGrades(httpClient *http.Client,ExamType ScoreType) ([]GradeEntry, erro
 	}
 	defer resp.Body.Close()
 
+	if resp.StatusCode != http.StatusOK {
+		return nil, fmt.Errorf("获取成绩失败, 状态码: %d", resp.StatusCode)
+	}
+
 	html, err := decodeResponseBody(resp)
 	if err != nil {
 		return nil, err
 	}
 
-	grades, err := ParseGradesHTML(html)
+	grades, err := parseGradesHTML(html)
 	if err != nil {
 		return nil, err
 	}
 
-	fmt.Printf("[成绩] 共获取 %d 条成绩记录\n", len(grades))
+	log.Info("成绩获取完成", "grade_count", len(grades))
 	return grades, nil
 }
 
 func FetchGPA(httpClient *http.Client) (*GPASummary, []GradeEntry, error) {
-	gpaURL := config.BaseURL + "/xfj/queryListXfj"
-	fmt.Println("[学分绩] 正在获取学分绩数据...")
+	gpaURL := config.Get().BaseURL + "/xfj/queryListXfj"
+	slog.Info("获取学分绩数据")
 
 	req, err := http.NewRequest("GET", gpaURL, nil)
 	if err != nil {
@@ -92,21 +98,25 @@ func FetchGPA(httpClient *http.Client) (*GPASummary, []GradeEntry, error) {
 	}
 	defer resp.Body.Close()
 
+	if resp.StatusCode != http.StatusOK {
+		return nil, nil, fmt.Errorf("获取学分绩失败, 状态码: %d", resp.StatusCode)
+	}
+
 	html, err := decodeResponseBody(resp)
 	if err != nil {
 		return nil, nil, err
 	}
 
-	summary, grades, err := ParseGPAHTML(html)
+	summary, grades, err := parseGPAHTML(html)
 	if err != nil {
 		return nil, nil, err
 	}
 
-	fmt.Printf("[学分绩] 共获取 %d 门课程明细\n", len(grades))
+	slog.Info("学分绩获取完成", "grade_count", len(grades))
 	return summary, grades, nil
 }
 
-func ParseGradesHTML(html string) ([]GradeEntry, error) {
+func parseGradesHTML(html string) ([]GradeEntry, error) {
 	doc, err := goquery.NewDocumentFromReader(strings.NewReader(html))
 	if err != nil {
 		return nil, err
@@ -173,7 +183,7 @@ func ParseGradesHTML(html string) ([]GradeEntry, error) {
 	return grades, nil
 }
 
-func ParseGPAHTML(html string) (*GPASummary, []GradeEntry, error) {
+func parseGPAHTML(html string) (*GPASummary, []GradeEntry, error) {
 	doc, err := goquery.NewDocumentFromReader(strings.NewReader(html))
 	if err != nil {
 		return nil, nil, err
@@ -254,4 +264,4 @@ func safeGet(arr []string, idx int) string {
 		return arr[idx]
 	}
 	return ""
-}
+}