feat: auto-subscribe push on login, better push logging

- Auto-subscribe to push on login, register, and session restore
- Guard against nil db in SendChannelNotification
- Log push send count per channel message
- Bump SW cache to v5

internal/push/handlers.go

@@ -185,7 +185,7 @@ func (h *Handler) SendPush(ctx context.Context, userID string, payload map[strin
 // SendChannelNotification sends a push notification to all server members (except the author)
 // when a new message is posted in a channel.
 func (h *Handler) SendChannelNotification(ctx context.Context, channelID, authorID, channelName, content string) {
-	if h.vapidPub == "" || h.vapidPriv == "" {
+	if h.vapidPub == "" || h.vapidPriv == "" || h.db == nil {
 		return
 	}
 
@@ -196,6 +196,8 @@ func (h *Handler) SendChannelNotification(ctx context.Context, channelID, author
 		return
 	}
 
+	h.logger.Info("sending push notifications", "channel", channelName, "author", authorID)
+
 	body := content
 	if len(body) > 200 {
 		body = body[:200] + "..."
@@ -221,6 +223,7 @@ func (h *Handler) SendChannelNotification(ctx context.Context, channelID, author
 	}
 	defer rows.Close()
 
+	sent := 0
 	for rows.Next() {
 		var userID, endpoint, p256dh, auth string
 		if err := rows.Scan(&userID, &endpoint, &p256dh, &auth); err != nil {
@@ -250,8 +253,12 @@ func (h *Handler) SendChannelNotification(ctx context.Context, channelID, author
 		}
 		if resp != nil {
 			resp.Body.Close()
+			if resp.StatusCode < 300 {
+				sent++
+			}
 		}
 	}
+	h.logger.Info("push notifications sent", "count", sent, "channel", channelName)
 }
 
 // GenerateVAPIDKeys is in cmd/keygen. Use github.com/SherClockHolmes/webpush-go directly.