feat: add NFT usernames and bot verification (#22)

Implements collectible usernames, official verification workflows, and third-party bot verification after maintainer protocol and migration review.

The composite activity/moderation rating remains an admin-only read model; Telegram Stars Rating wire fields stay unset pending a dedicated official-semantics implementation.

Reviewed-Head: 2796345775ea0f908fb7734601e5e1dee4b653b9
Original-Head: fa082b892fd5180c9c9bc53c81c21cf5d250a75b

Co-authored-by: Egor Egorov <business.egor.sg@gmail.com>

internal/app/verification/worker.go

@@ -0,0 +1,88 @@
+package verification
+
+import (
+	"context"
+	"time"
+
+	"go.uber.org/zap"
+)
+
+// defaultNotifyInterval matches the shipped
+// TELESRV_VERIFICATION_NOTIFY_INTERVAL default.
+const defaultNotifyInterval = 15 * time.Second
+
+// NotificationWorker drains the applicant-notification outbox.
+//
+// A decision is committed together with its outbox row, never with a message
+// send: @verifybot may be blocked, the applicant may be deleted, and the panel
+// must not wait on either. Delivery is therefore a separate, retrying cycle over
+// durable rows, and this worker is only its cadence.
+type NotificationWorker struct {
+	service  *Service
+	logger   *zap.Logger
+	interval time.Duration
+	batch    int
+}
+
+// NewNotificationWorker creates the periodic delivery worker. Non-positive
+// interval/batch fall back to the shipped defaults, matching the rating
+// recompute worker's contract.
+func NewNotificationWorker(service *Service, logger *zap.Logger, interval time.Duration, batch int) *NotificationWorker {
+	if logger == nil {
+		logger = zap.NewNop()
+	}
+	if interval <= 0 {
+		interval = defaultNotifyInterval
+	}
+	if batch <= 0 {
+		batch = defaultNotifyBatch
+	}
+	return &NotificationWorker{service: service, logger: logger, interval: interval, batch: batch}
+}
+
+// Run delivers one batch immediately and then on every tick until ctx is done. A
+// disabled or store-less service exits immediately with one explicit log line
+// instead of ticking forever over a no-op.
+func (w *NotificationWorker) Run(ctx context.Context) {
+	if w == nil {
+		return
+	}
+	if !w.service.Ready() {
+		w.logger.Info("verification notification worker disabled",
+			zap.Bool("enabled", w.service.Enabled()))
+		return
+	}
+	w.runOnce(ctx)
+	ticker := time.NewTicker(w.interval)
+	defer ticker.Stop()
+	for {
+		select {
+		case <-ctx.Done():
+			return
+		case <-ticker.C:
+			w.runOnce(ctx)
+		}
+	}
+}
+
+func (w *NotificationWorker) runOnce(ctx context.Context) {
+	if w == nil || w.service == nil {
+		return
+	}
+	delivered, err := w.service.RunNotificationCycle(ctx, w.batch)
+	if err != nil {
+		if ctx.Err() != nil {
+			return
+		}
+		w.logger.Warn("verification notification cycle failed",
+			zap.Int("delivered", delivered),
+			zap.Int("batch", w.batch),
+			zap.Error(err))
+		return
+	}
+	if delivered > 0 {
+		w.logger.Info("verification notification cycle completed",
+			zap.Int("delivered", delivered),
+			zap.Int("batch", w.batch))
+	}
+}