feat(cmd/mockserver): add standalone mock server for frontend development

Reuse MockSlurm + MockMinIO + TestEnv wiring pattern to create a standalone
binary that serves all API endpoints with in-memory SQLite and seed data.

- internal/mockserver/server.go: assembly logic (New/Close/Run), option pattern,
  4 accessors for seed data injection
- cmd/mockserver/main.go: CLI flags (--port, --seed, MOCK_PORT), 6 seed jobs
  in all 5 states + 2 seed applications, signal handling

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

cmd/mockserver/main.go

@@ -0,0 +1,131 @@
+package main
+
+import (
+	"context"
+	"encoding/json"
+	"flag"
+	"fmt"
+	"io"
+	"log"
+	"net/http"
+	"os"
+	"strconv"
+	"strings"
+
+	"gcy_hpc_server/internal/mockserver"
+	"gcy_hpc_server/internal/model"
+	"gcy_hpc_server/internal/slurm"
+)
+
+func main() {
+	defaultPort := 8080
+	if v := os.Getenv("MOCK_PORT"); v != "" {
+		if p, err := strconv.Atoi(v); err == nil {
+			defaultPort = p
+		}
+	}
+
+	port := flag.Int("port", defaultPort, "listen port")
+	seed := flag.Bool("seed", true, "inject seed data")
+	flag.Parse()
+
+	srv, err := mockserver.New(mockserver.WithPort(*port))
+	if err != nil {
+		log.Fatalf("failed to create server: %v", err)
+	}
+
+	if *seed {
+		injectSeedData(srv)
+	}
+
+	if err := srv.Run(); err != nil {
+		log.Fatalf("server error: %v", err)
+	}
+}
+
+func injectSeedData(srv *mockserver.Server) {
+	client := srv.MockSlurmHTTPClient()
+	baseURL := srv.MockSlurmURL()
+
+	type jobDef struct {
+		name      string
+		partition string
+		states    []string
+	}
+
+	jobs := []jobDef{
+		{"gpu-training-job", "gpu", nil},
+		{"data-processing", "normal", []string{"RUNNING"}},
+		{"benchmark-test", "normal", []string{"RUNNING"}},
+		{"model-evaluation", "gpu", []string{"RUNNING", "COMPLETED"}},
+		{"failed-script", "normal", []string{"RUNNING", "FAILED"}},
+		{"cancelled-job", "gpu", []string{"RUNNING", "CANCELLED"}},
+	}
+
+	mockSlurm := srv.MockSlurm()
+	for _, j := range jobs {
+		id, err := submitJob(client, baseURL, j.name, j.partition)
+		if err != nil {
+			log.Printf("warning: failed to submit job %q: %v", j.name, err)
+			continue
+		}
+		for _, state := range j.states {
+			mockSlurm.SetJobState(id, state)
+		}
+	}
+
+	appSvc := srv.ApplicationService()
+	ctx := context.Background()
+
+	apps := []model.CreateApplicationRequest{
+		{
+			Name:           "图像分类训练",
+			Description:    "基于ResNet的图像分类模型训练",
+			ScriptTemplate: "#!/bin/bash\n#SBATCH --job-name={{.Name}}\necho 'Running {{.Name}}'",
+		},
+		{
+			Name:           "数据处理流水线",
+			Description:    "ETL数据处理脚本",
+			ScriptTemplate: "#!/bin/bash\necho 'Processing data'",
+		},
+	}
+	for _, app := range apps {
+		if _, err := appSvc.CreateApplication(ctx, &app); err != nil {
+			log.Printf("warning: failed to create application %q: %v", app.Name, err)
+		}
+	}
+
+	log.Println("Seeded 6 jobs (1 PENDING, 2 RUNNING, 1 COMPLETED, 1 FAILED, 1 CANCELLED) and 2 applications")
+}
+
+func submitJob(client *http.Client, baseURL, name, partition string) (int32, error) {
+	body := fmt.Sprintf(
+		`{"script":"#!/bin/bash\necho %s","job":{"name":"%s","partition":"%s"}}`,
+		name, name, partition,
+	)
+	req, err := http.NewRequest("POST", baseURL+"/slurm/v0.0.40/job/submit", strings.NewReader(body))
+	if err != nil {
+		return 0, fmt.Errorf("create request: %w", err)
+	}
+	req.Header.Set("Content-Type", "application/json")
+
+	resp, err := client.Do(req)
+	if err != nil {
+		return 0, fmt.Errorf("do request: %w", err)
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		b, _ := io.ReadAll(resp.Body)
+		return 0, fmt.Errorf("unexpected status %d: %s", resp.StatusCode, b)
+	}
+
+	var result slurm.OpenapiJobSubmitResponse
+	if err := json.NewDecoder(resp.Body).Decode(&result); err != nil {
+		return 0, fmt.Errorf("decode response: %w", err)
+	}
+	if result.JobID == nil {
+		return 0, fmt.Errorf("no job_id in response")
+	}
+	return *result.JobID, nil
+}