Show a slack target's retry setting in the target list (closes #395)

The target list showed only the masked webhook URL for a slack
target, though its edit page saves a retry setting and delivery
honours it. It now shows the same retry fields, with the same
labels and wording, as an http target.

Model: opus-5-5

internal/delivery/target_config_view.go

@@ -97,7 +97,7 @@ func targetConfigFields(
 ) []ConfigField {
 	switch t.Type {
 	case database.TargetTypeSlack:
-		return slackConfigFields(t.Config)
+		return slackConfigFields(t)
 	case database.TargetTypeHTTP:
 		return httpConfigFields(t)
 	case database.TargetTypeDatabase:
@@ -119,18 +119,21 @@ func unavailableConfigFields() []ConfigField {
 	}}
 }
 
-// slackConfigFields describes a Slack target. Only the masked
-// webhook URL is shown; the full URL is the credential.
-func slackConfigFields(configJSON string) []ConfigField {
-	cfg, err := parseSlackConfig(configJSON)
+// slackConfigFields describes a Slack target: its masked
+// webhook URL and its retry settings. Only the masked URL is
+// shown; the full URL is the credential.
+func slackConfigFields(t *database.Target) []ConfigField {
+	cfg, err := parseSlackConfig(t.Config)
 	if err != nil {
 		return unavailableConfigFields()
 	}
 
-	return []ConfigField{{
+	fields := []ConfigField{{
 		Label: "Webhook URL",
 		Value: cfg.MaskedWebhookURL(),
 	}}
+
+	return append(fields, retryFields(t)...)
 }
 
 // httpConfigFields describes an HTTP target: its destination

internal/delivery/target_config_view_test.go

@@ -158,7 +158,10 @@ func TestNewTargetViews_DeletedTarget(t *testing.T) {
 	)
 	assert.Equal(
 		t,
-		map[string]string{"Webhook URL": slackMaskedURL},
+		map[string]string{
+			"Webhook URL": slackMaskedURL,
+			"Max Retries": "0 (fire-and-forget)",
+		},
 		fieldMap(view.Config),
 	)
 }
@@ -189,7 +192,32 @@ func TestNewTargetViews_Slack(t *testing.T) {
 
 	assert.Equal(
 		t,
-		map[string]string{"Webhook URL": slackMaskedURL},
+		map[string]string{
+			"Webhook URL": slackMaskedURL,
+			"Max Retries": "0 (fire-and-forget)",
+		},
+		fieldMap(view.Config),
+	)
+}
+
+// TestNewTargetViews_SlackRetries proves a Slack target shows
+// its retry settings the same way an HTTP target does.
+func TestNewTargetViews_SlackRetries(t *testing.T) {
+	t.Parallel()
+
+	target := slackTarget()
+	target.MaxRetries = 2
+	target.MaxQueueSize = 100
+
+	view := viewFor(t, target)
+
+	assert.Equal(
+		t,
+		map[string]string{
+			"Webhook URL":    slackMaskedURL,
+			"Max Retries":    "2",
+			"Max Queue Size": "100",
+		},
 		fieldMap(view.Config),
 	)
 }