refactor(squad): inject Options + backend factory, drop config.Config dependency

KTD1 first step (in-repo decoupling, behavior preserved):
- squad.Options{BackendName, BackendTimeout, DataDir, NewBackend} replaces
  *config.Config; defaults applied in withDefaults
- backend construction injected by caller (bizdev assembly): credentials,
  environment and concurrency stay product-side; nil factory fails closed
  instead of silently degrading to Stub
- verified: go vet ./... clean, squad/bizdev short tests pass

internal/bizdev/service.go

@@ -10,6 +10,7 @@ import (
 	"strings"
 	"time"
 
+	"chat-agent-system/internal/agent"
 	"chat-agent-system/internal/app/uow"
 	"chat-agent-system/internal/authz"
 	"chat-agent-system/internal/config"
@@ -192,7 +193,14 @@ func NewService(cfg *config.Config) (*Service, error) {
 	svc := &Service{
 		cfg:             cfg,
 		kb:              kb.NewClient(cfg),
-		squad:           squad.NewService(cfg),
+		squad: squad.NewService(squad.Options{
+			BackendName:    cfg.AgentBackend,
+			BackendTimeout: cfg.AgentTimeout,
+			DataDir:        cfg.DataDir,
+			NewBackend: func(name string) agent.Backend {
+				return agent.NewBackend(name, cfg)
+			},
+		}),
 		ctxMgr:          ctxMgr,
 		cas:             casStore,
 		materialIndex:   matIndex,

internal/squad/service.go

@@ -10,7 +10,6 @@ import (
 	"time"
 
 	"chat-agent-system/internal/agent"
-	"chat-agent-system/internal/config"
 	"chat-agent-system/internal/quote"
 	"chat-agent-system/internal/stream"
 	"chat-agent-system/internal/workflowdef"
@@ -109,18 +108,42 @@ type SquadService interface {
 	ResumeOrModifyWorkspace(ctx context.Context, req ModifyWorkflowRequest) (*SquadRunResult, error)
 }
 
+// Options 是 Squad 依赖注入的唯一配置面；不反向依赖主仓 config.Config，
+// 为独立模块做准备（见多仓方案 KTD1）。
+type Options struct {
+	// BackendName 为执行后端名（空 = 由调用方默认）。
+	BackendName string
+	// BackendTimeout 为单次执行超时；零值由调用方默认。
+	BackendTimeout time.Duration
+	// DataDir 为工作区根（任务目录挂在其下）。
+	DataDir string
+	// NewBackend 由调用方注入的后端工厂（Core 装配：凭证、环境、并发上限
+	// 留在产品侧）。nil 时返回错误，不静默降级 Stub。
+	NewBackend func(name string) agent.Backend
+}
+
+func (o Options) withDefaults() Options {
+	if o.BackendName == "" {
+		o.BackendName = "pi-agent"
+	}
+	if o.BackendTimeout <= 0 {
+		o.BackendTimeout = 10 * time.Minute
+	}
+	return o
+}
+
 // Service SquadService 实现
 type Service struct {
-	cfg    *config.Config
+	opts   Options
 	engine *WorkspaceEngine
 	driver *WorkflowDriver
 	gate   *QualityGate
 }
 
-func NewService(cfg *config.Config) *Service {
+func NewService(opts Options) *Service {
 	engine := NewWorkspaceEngine()
 	return &Service{
-		cfg:    cfg,
+		opts:   opts.withDefaults(),
 		engine: engine,
 		driver: NewWorkflowDriver(engine),
 		gate:   NewQualityGate(),
@@ -207,12 +230,12 @@ func (s *Service) ExecuteTask(ctx context.Context, req SquadRunRequest) (*SquadR
 	workDir := req.WorkDir
 	if workDir == "" {
 		ts := time.Now().UnixNano()
-		workDir = filepath.Join(s.cfg.DataDir, "workspaces", "bizdev", fmt.Sprintf("%s_%d", req.TaskKey, ts))
+		workDir = filepath.Join(s.opts.DataDir, "workspaces", "bizdev", fmt.Sprintf("%s_%d", req.TaskKey, ts))
 	}
 
 	backendName := req.Backend
 	if backendName == "" {
-		backendName = s.cfg.AgentBackend
+		backendName = s.opts.BackendName
 	}
 
 	// 1. 初始化工作区目录体系
@@ -258,10 +281,13 @@ func (s *Service) ExecuteTask(ctx context.Context, req SquadRunRequest) (*SquadR
 		streamer.EmitPhase("squad_assembly", fmt.Sprintf("正在组建并启动【%s】智能体小队（后端: %s）...", TaskArtifactTitle(req.TaskKey), backendName), "leader", 0, 0, 5)
 	}
 
-	backend := agent.NewBackend(backendName, s.cfg)
+	if s.opts.NewBackend == nil {
+		return nil, fmt.Errorf("squad: NewBackend factory not injected")
+	}
+	backend := s.opts.NewBackend(backendName)
 	timeout := req.Timeout
 	if timeout <= 0 {
-		timeout = s.cfg.AgentTimeout
+		timeout = s.opts.BackendTimeout
 	}
 	execOpts := ExecuteOptions{
 		Timeout:    timeout,
@@ -397,9 +423,12 @@ func repairBudgetForSquadTask(req SquadRunRequest) int {
 func (s *Service) ExecuteWorkflow(ctx context.Context, wsDir string, backendName string, opts ExecuteOptions) (*SquadRunResult, error) {
 	start := time.Now()
 	if backendName == "" {
-		backendName = s.cfg.AgentBackend
+		backendName = s.opts.BackendName
 	}
-	backend := agent.NewBackend(backendName, s.cfg)
+	if s.opts.NewBackend == nil {
+		return nil, fmt.Errorf("squad: NewBackend factory not injected")
+	}
+	backend := s.opts.NewBackend(backendName)
 
 	execRes, err := s.driver.Execute(ctx, wsDir, backend, opts)
 	if err != nil {
@@ -491,12 +520,12 @@ func (s *Service) ResumeOrModifyWorkspace(ctx context.Context, req ModifyWorkflo
 
 	backendName := req.Backend
 	if backendName == "" {
-		backendName = s.cfg.AgentBackend
+		backendName = s.opts.BackendName
 	}
 
 	timeout := req.Timeout
 	if timeout <= 0 {
-		timeout = s.cfg.AgentTimeout
+		timeout = s.opts.BackendTimeout
 	}
 
 	opts := ExecuteOptions{