feat(maintenance): add policy executor and config provider

ConfigProvider, PolicyExecutor, DBStatsProvider, scheduler и safety; зависимость robfig/cron/v3.

Co-authored-by: Cursor <[email protected]>

internal/maintenance/scheduler.go

@@ -0,0 +1,93 @@
+package maintenance
+
+import (
+	"context"
+	"fmt"
+	"log"
+	"strings"
+	"sync"
+	"time"
+
+	"evobgp/internal/jobs"
+
+	"github.com/robfig/cron/v3"
+)
+
+// StartScheduler enqueues maintenance_policy_run jobs when cron schedules match.
+func StartScheduler(ctx context.Context, provider *ConfigProvider, reg *jobs.Registry, tick time.Duration) {
+	if provider == nil || reg == nil {
+		return
+	}
+	if tick <= 0 {
+		tick = 30 * time.Second
+	}
+	go func() {
+		parser := cron.NewParser(cron.Minute | cron.Hour | cron.Dom | cron.Month | cron.Dow)
+		var mu sync.Mutex
+		schedules := map[string]cron.Schedule{}
+		lastFired := map[string]time.Time{}
+
+		rebuild := func() {
+			mu.Lock()
+			defer mu.Unlock()
+			schedules = map[string]cron.Schedule{}
+			for _, p := range provider.Snapshot() {
+				if p == nil || !p.Enabled || strings.TrimSpace(p.Schedule) == "" {
+					continue
+				}
+				sched, err := parser.Parse(p.Schedule)
+				if err != nil {
+					log.Printf("maintenance: invalid cron for policy %s: %v", p.ID, err)
+					continue
+				}
+				schedules[p.ID] = sched
+			}
+		}
+
+		rebuild()
+		t := time.NewTicker(tick)
+		defer t.Stop()
+		for {
+			select {
+			case <-ctx.Done():
+				return
+			case <-t.C:
+				rebuild()
+				now := time.Now().UTC()
+				mu.Lock()
+				for _, p := range provider.Snapshot() {
+					if p == nil || !p.Enabled {
+						continue
+					}
+					sched, ok := schedules[p.ID]
+					if !ok {
+						continue
+					}
+					prev := lastFired[p.ID]
+					if prev.IsZero() {
+						prev = now.Add(-time.Minute)
+					}
+					next := sched.Next(prev)
+					if next.After(now) {
+						continue
+					}
+					slot := next.Unix() / 60
+					if lf, ok := lastFired[p.ID]; ok && lf.Unix()/60 == slot {
+						continue
+					}
+					lastFired[p.ID] = next
+					dry := p.DryRunEnabled
+					idem := fmt.Sprintf("maint-%s-%d", p.ID, slot)
+					key := idem
+					_, _, _ = reg.Enqueue("", "maintenance_policy_run", &key, nil, map[string]any{
+						"policy_id": p.ID,
+						"dry_run":   dry,
+						"trigger":   "scheduler",
+					})
+				}
+				mu.Unlock()
+			}
+		}
+	}()
+	log.Printf("maintenance: policy scheduler started (tick=%s)", tick)
+}