feat: add webhook event history UI page

Add a per-app webhook event history page at /apps/{id}/webhooks that
displays received webhook events with their match/no-match status,
event type, branch, commit SHA (linked to commit URL when available),
and timestamp.

Changes:
- Add webhook_events.html template following existing UI patterns
- Add HandleAppWebhookEvents handler in webhook_events.go
- Register GET /apps/{id}/webhooks route
- Register webhook_events.html in template cache
- Add ShortCommit() method to WebhookEvent model
- Add 'Event History' link to app detail Webhook URL section

internal/handlers/webhook_events.go

@@ -0,0 +1,56 @@
+package handlers
+
+import (
+	"net/http"
+
+	"github.com/go-chi/chi/v5"
+
+	"sneak.berlin/go/upaas/internal/models"
+	"sneak.berlin/go/upaas/templates"
+)
+
+// webhookEventsLimit is the number of webhook events to show in history.
+const webhookEventsLimit = 100
+
+// HandleAppWebhookEvents returns the webhook event history handler.
+func (h *Handlers) HandleAppWebhookEvents() http.HandlerFunc {
+	tmpl := templates.GetParsed()
+
+	return func(writer http.ResponseWriter, request *http.Request) {
+		appID := chi.URLParam(request, "id")
+
+		application, findErr := models.FindApp(request.Context(), h.db, appID)
+		if findErr != nil {
+			h.log.Error("failed to find app", "error", findErr)
+			http.Error(writer, "Internal Server Error", http.StatusInternalServerError)
+
+			return
+		}
+
+		if application == nil {
+			http.NotFound(writer, request)
+
+			return
+		}
+
+		events, eventsErr := application.GetWebhookEvents(
+			request.Context(),
+			webhookEventsLimit,
+		)
+		if eventsErr != nil {
+			h.log.Error("failed to get webhook events",
+				"error", eventsErr,
+				"app", appID,
+			)
+
+			events = []*models.WebhookEvent{}
+		}
+
+		data := h.addGlobals(map[string]any{
+			"App":    application,
+			"Events": events,
+		}, request)
+
+		h.renderTemplate(writer, tmpl, "webhook_events.html", data)
+	}
+}

internal/models/webhook_event.go

@@ -52,6 +52,20 @@ func (w *WebhookEvent) Reload(ctx context.Context) error {
 	return w.scan(row)
 }
 
+// ShortCommit returns a truncated commit SHA for display.
+func (w *WebhookEvent) ShortCommit() string {
+	if !w.CommitSHA.Valid {
+		return ""
+	}
+
+	sha := w.CommitSHA.String
+	if len(sha) > shortCommitLength {
+		return sha[:shortCommitLength]
+	}
+
+	return sha
+}
+
 func (w *WebhookEvent) insert(ctx context.Context) error {
 	query := `
 		INSERT INTO webhook_events (

internal/server/routes.go

@@ -70,6 +70,7 @@ func (s *Server) SetupRoutes() {
 			r.Post("/apps/{id}/deploy", s.handlers.HandleAppDeploy())
 			r.Post("/apps/{id}/deployments/cancel", s.handlers.HandleCancelDeploy())
 			r.Get("/apps/{id}/deployments", s.handlers.HandleAppDeployments())
+			r.Get("/apps/{id}/webhooks", s.handlers.HandleAppWebhookEvents())
 			r.Get("/apps/{id}/deployments/{deploymentID}/logs", s.handlers.HandleDeploymentLogsAPI())
 			r.Get("/apps/{id}/deployments/{deploymentID}/download", s.handlers.HandleDeploymentLogDownload())
 			r.Get("/apps/{id}/logs", s.handlers.HandleAppLogs())