fix(phase3): skip templateless domains in scheduler; block CGNAT range in webhook SSRF guard

Domains imported without a template (TemplateID == nil) are a valid,
unconfigured state, not a failure — RunOnce now skips them before
calling checkDomain instead of letting LoadDomain's "no template" error
turn into StatusError and a spammy unknown->error notification.

isBlockedIP now also rejects 100.64.0.0/10 (RFC 6598 carrier-grade
NAT), which net.IP.IsPrivate() does not cover, closing an SSRF gap in
the webhook destination guard (both the pre-request check and the
per-dial check use isBlockedIP).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01BwxdSt4reTm7Dj1oxRvpP3

internal/notify/webhook.go

@@ -83,17 +83,34 @@ func isAllowedURL(rawurl string) error {
 	return nil
 }
 
+// cgnatBlock is the shared address space reserved for carrier-grade NAT
+// (RFC 6598, 100.64.0.0/10). net.IP.IsPrivate() only covers RFC1918/RFC4193
+// and does not treat this range as private, so it must be checked
+// explicitly or CGNAT-addressed internal services would be reachable via
+// webhook SSRF.
+var cgnatBlock = func() *net.IPNet {
+	_, block, err := net.ParseCIDR("100.64.0.0/10")
+	if err != nil {
+		panic(err)
+	}
+	return block
+}()
+
 // isBlockedIP reports whether ip must never be connected to: loopback,
-// private (RFC1918 etc.), link-local, unspecified, or multicast. Used both
-// by isAllowedURL's pre-request check and by dialControl's per-connection
-// check.
+// private (RFC1918 etc.), link-local, unspecified, multicast, or
+// carrier-grade NAT (RFC 6598). Used both by isAllowedURL's pre-request
+// check and by dialControl's per-connection check.
 func isBlockedIP(ip net.IP) bool {
+	if v4 := ip.To4(); v4 != nil {
+		ip = v4
+	}
 	return ip.IsLoopback() ||
 		ip.IsPrivate() ||
 		ip.IsLinkLocalUnicast() ||
 		ip.IsLinkLocalMulticast() ||
 		ip.IsUnspecified() ||
-		ip.IsMulticast()
+		ip.IsMulticast() ||
+		cgnatBlock.Contains(ip)
 }
 
 // dialControl returns a net.Dialer.Control function enforcing the SSRF guard