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; a blank field on the add target form gives 1, and on the
edit form keeps the stored value. 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)