feat: add cron tool integration with agent

- Add adhocore/gronx dependency for cron expression parsing
- Fix CronService race conditions and add cron expression support
- Add CronTool with add/list/remove/enable/disable actions
- Add ContextualTool interface for tools needing channel/chatID context
- Add ProcessDirectWithChannel to AgentLoop for cron job execution
- Register CronTool in gateway and wire up onJob handler
- Fix slice bounds panic in addJob for short messages

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

cmd/picoclaw/main.go

@@ -27,6 +27,7 @@ import (
 	"github.com/sipeed/picoclaw/pkg/logger"
 	"github.com/sipeed/picoclaw/pkg/providers"
 	"github.com/sipeed/picoclaw/pkg/skills"
+	"github.com/sipeed/picoclaw/pkg/tools"
 	"github.com/sipeed/picoclaw/pkg/voice"
 )
 
@@ -551,8 +552,20 @@ func gatewayCmd() {
 		})
 
 	cronStorePath := filepath.Join(filepath.Dir(getConfigPath()), "cron", "jobs.json")
+
+	// Create cron service first (onJob handler set after CronTool creation)
 	cronService := cron.NewCronService(cronStorePath, nil)
 
+	// Create and register CronTool
+	cronTool := tools.NewCronTool(cronService, agentLoop)
+	agentLoop.RegisterTool(cronTool)
+
+	// Now set the onJob handler for cron service
+	cronService.SetOnJob(func(job *cron.CronJob) (string, error) {
+		result := cronTool.ExecuteJob(context.Background(), job)
+		return result, nil
+	})
+
 	heartbeatService := heartbeat.NewHeartbeatService(
 		cfg.WorkspacePath(),
 		nil,
@@ -745,7 +758,7 @@ func cronHelp() {
 
 func cronListCmd(storePath string) {
 	cs := cron.NewCronService(storePath, nil)
-	jobs := cs.ListJobs(false)
+	jobs := cs.ListJobs(true)  // Show all jobs, including disabled
 
 	if len(jobs) == 0 {
 		fmt.Println("No scheduled jobs.")