feat(daemon): agent-driven repo checkout with bare clone cache

Agents now decide which repo to use based on issue context and check out
repos on demand via `multica repo checkout <url>`. Workspace repos are
cached locally as bare clones for fast worktree creation.

Key changes:
- Add repocache package for bare clone management (clone, fetch, worktree)
- Add `multica repo checkout` CLI command that talks to local daemon
- Add POST /repo/checkout endpoint on daemon health server
- Pass workspace repos metadata through register + task claim responses
- Remove pre-created worktrees from execenv (workdir starts empty)
- Update CLAUDE.md template to instruct agents to use `multica repo checkout`
- Pass MULTICA_DAEMON_PORT, WORKSPACE_ID, AGENT_NAME, TASK_ID env vars to agent

server/cmd/multica/cmd_repo.go

@@ -0,0 +1,92 @@
+package main
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"os"
+	"time"
+
+	"github.com/spf13/cobra"
+)
+
+var repoCmd = &cobra.Command{
+	Use:   "repo",
+	Short: "Manage repositories",
+}
+
+var repoCheckoutCmd = &cobra.Command{
+	Use:   "checkout <url>",
+	Short: "Check out a repository into the working directory",
+	Long:  "Creates a git worktree from the daemon's bare clone cache. Used by agents to check out repos on demand.",
+	Args:  cobra.ExactArgs(1),
+	RunE:  runRepoCheckout,
+}
+
+func init() {
+	repoCmd.AddCommand(repoCheckoutCmd)
+}
+
+func runRepoCheckout(cmd *cobra.Command, args []string) error {
+	repoURL := args[0]
+
+	daemonPort := os.Getenv("MULTICA_DAEMON_PORT")
+	if daemonPort == "" {
+		return fmt.Errorf("MULTICA_DAEMON_PORT not set (this command is intended to be run by an agent inside a daemon task)")
+	}
+
+	workspaceID := os.Getenv("MULTICA_WORKSPACE_ID")
+	agentName := os.Getenv("MULTICA_AGENT_NAME")
+	taskID := os.Getenv("MULTICA_TASK_ID")
+
+	// Use current working directory as the checkout target.
+	workDir, err := os.Getwd()
+	if err != nil {
+		return fmt.Errorf("get working directory: %w", err)
+	}
+
+	reqBody := map[string]string{
+		"url":          repoURL,
+		"workspace_id": workspaceID,
+		"workdir":      workDir,
+		"agent_name":   agentName,
+		"task_id":      taskID,
+	}
+
+	data, err := json.Marshal(reqBody)
+	if err != nil {
+		return fmt.Errorf("encode request: %w", err)
+	}
+
+	client := &http.Client{Timeout: 5 * time.Minute}
+	resp, err := client.Post(
+		fmt.Sprintf("http://127.0.0.1:%s/repo/checkout", daemonPort),
+		"application/json",
+		bytes.NewReader(data),
+	)
+	if err != nil {
+		return fmt.Errorf("connect to daemon: %w", err)
+	}
+	defer resp.Body.Close()
+
+	body, _ := io.ReadAll(resp.Body)
+
+	if resp.StatusCode != http.StatusOK {
+		return fmt.Errorf("checkout failed: %s", string(body))
+	}
+
+	var result struct {
+		Path       string `json:"path"`
+		BranchName string `json:"branch_name"`
+	}
+	if err := json.Unmarshal(body, &result); err != nil {
+		return fmt.Errorf("parse response: %w", err)
+	}
+
+	fmt.Fprintf(os.Stdout, "%s\n", result.Path)
+	fmt.Fprintf(os.Stderr, "Checked out %s → %s (branch: %s)\n", repoURL, result.Path, result.BranchName)
+
+	return nil
+}

server/cmd/multica/main.go

@@ -31,6 +31,7 @@ func init() {
 	rootCmd.AddCommand(workspaceCmd)
 	rootCmd.AddCommand(configCmd)
 	rootCmd.AddCommand(issueCmd)
+	rootCmd.AddCommand(repoCmd)
 	rootCmd.AddCommand(versionCmd)
 }