Wait for webhook deployments in handlers tests instead of sleeping (closes #211)

`TestHandleWebhookProcessesValidWebhook` waited for the background deployment with a 100 ms sleep, so its temp directory could be removed while the deployment was still writing its log there, and the test failed now and then. It now waits with the webhook service's `WaitForDeployments`, the fix already applied to the webhook service tests for #198. The test context keeps the webhook service it already built. No other handlers test can start a deployment. No production code change.

Model: opus-5-5

TODO.md

@@ -20,6 +20,10 @@ regress.
 
 # Completed Steps
 
+- 2026-09-23: Fixed the flaky `t.TempDir` cleanup race in `internal/handlers`
+  (the one fixed in `internal/service/webhook` by #198):
+  `TestHandleWebhookProcessesValidWebhook` now waits with the webhook service's
+  `WaitForDeployments` instead of sleeping (#211).
 - 2026-09-22: Vendored the canonical prettier/format toolchain from the
   `sneak/prompts` scaffold: added `.prettierrc` (tabWidth 4, proseWrap always),
   pinned `package.json` + `yarn.lock` (prettier 3.8.1), taught

internal/handlers/handlers_test.go

@@ -8,7 +8,6 @@ import (
 	"strconv"
 	"strings"
 	"testing"
-	"time"
 
 	"github.com/go-chi/chi/v5"
 	"github.com/stretchr/testify/assert"
@@ -43,6 +42,7 @@ type testContext struct {
 	authSvc    *auth.Service
 	appSvc     *app.Service
 	deploySvc  *deploy.Service
+	webhookSvc *webhook.Service
 	middleware *middleware.Middleware
 }
 
@@ -188,6 +188,7 @@ func setupTestHandlers(t *testing.T) *testContext {
 		authSvc:    authSvc,
 		appSvc:     appSvc,
 		deploySvc:  deploySvc,
+		webhookSvc: webhookSvc,
 		middleware: mw,
 	}
 }
@@ -1213,8 +1214,7 @@ func TestHandleWebhookProcessesValidWebhook(t *testing.T) {
 
 	assert.Equal(t, http.StatusOK, recorder.Code)
 
-	// Allow async deployment goroutine to complete before test cleanup.
-	// The deployment will fail quickly (docker not connected) but we need
-	// to wait for it to finish to avoid temp directory cleanup race.
-	time.Sleep(100 * time.Millisecond)
+	// Wait for the async deployment goroutine to finish so its writes
+	// under the temp dir complete before test cleanup.
+	testCtx.webhookSvc.WaitForDeployments()
 }