Store a target's number of delivery attempts, at least one (closes #540)

Target.MaxRetries (max_retries) becomes Target.MaxAttempts
(max_attempts), and the form field, parser and ceiling are renamed to
match. 1 is a single attempt with no circuit breaker; above 1 retries
behind the breaker up to that many attempts. Both target forms refuse
0 and less and default a blank field to 1. The target page shows the
plain number, and the README's two paragraphs on 0 against 1 become
one sentence.

Model: opus-5-5

internal/delivery/engine_integration_test.go

@@ -170,7 +170,7 @@ func iTask(
 	d database.Delivery,
 	event database.Event,
 	webhookID, targetID, name, config string,
-	maxRetries, attemptNum int,
+	maxAttempts, attemptNum int,
 	body *string,
 ) delivery.Task {
 	return delivery.Task{
@@ -181,7 +181,7 @@ func iTask(
 		TargetName:   name,
 		TargetType:   database.TargetTypeHTTP,
 		TargetConfig: config,
-		MaxRetries:   maxRetries,
+		MaxAttempts:  maxAttempts,
 		Method:       event.Method,
 		Headers:      event.Headers,
 		ContentType:  event.ContentType,
@@ -242,7 +242,7 @@ func TestProcessNewTask_InlineBody(t *testing.T) {
 	cfg := iHTTPConfig(ts.URL)
 	task := iTask(
 		d, event, s.WebhookID, targetID,
-		"test-target", cfg, 0, 1, &bodyStr,
+		"test-target", cfg, 1, 1, &bodyStr,
 	)
 
 	s.Engine.ExportProcessNewTask(
@@ -293,7 +293,7 @@ func TestProcessNewTask_LargeBody_FetchFromDB(
 	cfg := iHTTPConfig(ts.URL)
 	task := iTask(
 		d, event, s.WebhookID, targetID,
-		"test-large", cfg, 0, 1, nil,
+		"test-large", cfg, 1, 1, nil,
 	)
 
 	s.Engine.ExportProcessNewTask(
@@ -320,7 +320,7 @@ func TestProcessNewTask_InvalidWebhookID(t *testing.T) {
 		TargetName:   "test",
 		TargetType:   database.TargetTypeHTTP,
 		TargetConfig: iHTTPConfig("http://localhost:9999"),
-		MaxRetries:   0,
+		MaxAttempts:  1,
 		Body:         nil,
 		AttemptNum:   1,
 	}
@@ -645,7 +645,7 @@ func TestRecoverPendingDeliveries(t *testing.T) {
 
 	iCreateTarget(t, s.MainDB, targetID,
 		s.WebhookID, "recovery-target",
-		database.TargetTypeLog, "", 0,
+		database.TargetTypeLog, "", 1,
 	)
 
 	iSeedPendingDeliveries(
@@ -686,17 +686,17 @@ func iCreateTarget(
 	targetID, webhookID, name string,
 	targetType database.TargetType,
 	config string,
-	maxRetries int,
+	maxAttempts int,
 ) {
 	t.Helper()
 
 	target := database.Target{
-		WebhookID:  webhookID,
-		Name:       name,
-		Type:       targetType,
-		Active:     true,
-		Config:     config,
-		MaxRetries: maxRetries,
+		WebhookID:   webhookID,
+		Name:        name,
+		Type:        targetType,
+		Active:      true,
+		Config:      config,
+		MaxAttempts: maxAttempts,
 	}
 	target.ID = targetID
 
@@ -1077,7 +1077,7 @@ func TestRecoverInFlight_WithPendingDeliveries(
 
 	iCreateTarget(t, s.MainDB, targetID,
 		s.WebhookID, "recover-target",
-		database.TargetTypeLog, "", 0,
+		database.TargetTypeLog, "", 1,
 	)
 
 	event := iSeedEvent(
@@ -1232,7 +1232,7 @@ func TestDeliverHTTP_CustomTargetHeaders(t *testing.T) {
 	task := iTask(
 		d, event, s.WebhookID, targetID,
 		"auth-target", string(cfgJSON),
-		0, 1, &bodyStr,
+		1, 1, &bodyStr,
 	)
 
 	s.Engine.ExportProcessNewTask(
@@ -1277,7 +1277,7 @@ func TestDeliverHTTP_TargetTimeout(t *testing.T) {
 
 	task, d := iHTTPTaskAndDelivery(
 		event, del, "timeout-target",
-		string(cfgJSON), 0, 1,
+		string(cfgJSON), 1, 1,
 	)
 
 	e.ExportDeliverHTTP(context.TODO(), db, d, task)
@@ -1339,7 +1339,7 @@ func TestDeliverHTTP_CutsStoredResponseAtMaxBodyLog(
 	bodyStr := event.Body
 	task := iTask(
 		del, event, s.WebhookID, targetID,
-		"cut-target", cfgJSON, 0, 1, &bodyStr,
+		"cut-target", cfgJSON, 1, 1, &bodyStr,
 	)
 
 	s.Engine.ExportProcessNewTask(context.TODO(), &task)
@@ -1403,7 +1403,7 @@ func iHTTPTaskAndDelivery(
 	event database.Event,
 	del database.Delivery,
 	name, config string,
-	maxRetries, attemptNum int,
+	maxAttempts, attemptNum int,
 ) (*delivery.Task, *database.Delivery) {
 	task := &delivery.Task{
 		DeliveryID:   del.ID,
@@ -1413,7 +1413,7 @@ func iHTTPTaskAndDelivery(
 		TargetName:   name,
 		TargetType:   database.TargetTypeHTTP,
 		TargetConfig: config,
-		MaxRetries:   maxRetries,
+		MaxAttempts:  maxAttempts,
 		AttemptNum:   attemptNum,
 	}
 
@@ -1466,7 +1466,7 @@ func TestDeliverHTTP_InvalidConfig(t *testing.T) {
 	)
 
 	task, d := iHTTPTaskAndDelivery(
-		event, del, "bad-config", `not-json`, 0, 1,
+		event, del, "bad-config", `not-json`, 1, 1,
 	)
 
 	e.ExportDeliverHTTP(context.TODO(), db, d, task)
@@ -1490,7 +1490,7 @@ func TestDeliverHTTP_InvalidConfigUnrecordedStaysPending(t *testing.T) {
 	)
 
 	task, d := iHTTPTaskAndDelivery(
-		event, del, "bad-config", `not-json`, 0, 1,
+		event, del, "bad-config", `not-json`, 1, 1,
 	)
 
 	require.NoError(t, db.Exec("drop table delivery_results").Error)