Backend improvements: views, fields_get, session, RPC stubs

- Improved auto-generated list/form/search views with priority fields,
  two-column form layout, statusbar widget, notebook for O2M fields
- Enhanced fields_get with currency_field, compute, related metadata
- Fixed session handling: handleSessionInfo/handleSessionCheck use real
  session from cookie instead of hardcoded values
- Added read_progress_bar and activity_format RPC stubs
- Improved bootstrap translations with lang_parameters
- Added "contacts" to session modules list

Server starts successfully: 14 modules, 93 models, 378 XML templates,
503 JS modules transpiled — all from local frontend/ directory.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

pkg/service/cron.go

@@ -0,0 +1,68 @@
+package service
+
+import (
+	"context"
+	"log"
+	"sync"
+	"time"
+
+	"github.com/jackc/pgx/v5/pgxpool"
+)
+
+// CronJob defines a scheduled task.
+type CronJob struct {
+	Name     string
+	Interval time.Duration
+	Handler  func(ctx context.Context, pool *pgxpool.Pool) error
+	running  bool
+}
+
+// CronScheduler manages periodic jobs.
+type CronScheduler struct {
+	jobs   []*CronJob
+	mu     sync.Mutex
+	ctx    context.Context
+	cancel context.CancelFunc
+}
+
+// NewCronScheduler creates a new scheduler.
+func NewCronScheduler() *CronScheduler {
+	ctx, cancel := context.WithCancel(context.Background())
+	return &CronScheduler{ctx: ctx, cancel: cancel}
+}
+
+// Register adds a job to the scheduler.
+func (s *CronScheduler) Register(job *CronJob) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	s.jobs = append(s.jobs, job)
+}
+
+// Start begins running all registered jobs.
+func (s *CronScheduler) Start(pool *pgxpool.Pool) {
+	for _, job := range s.jobs {
+		go s.runJob(job, pool)
+	}
+	log.Printf("cron: started %d jobs", len(s.jobs))
+}
+
+// Stop cancels all running jobs.
+func (s *CronScheduler) Stop() {
+	s.cancel()
+}
+
+func (s *CronScheduler) runJob(job *CronJob, pool *pgxpool.Pool) {
+	ticker := time.NewTicker(job.Interval)
+	defer ticker.Stop()
+
+	for {
+		select {
+		case <-s.ctx.Done():
+			return
+		case <-ticker.C:
+			if err := job.Handler(s.ctx, pool); err != nil {
+				log.Printf("cron: %s error: %v", job.Name, err)
+			}
+		}
+	}
+}