Let an entrypoint's description be edited in place (closes #392)

Each entrypoint on the webhook page has an Edit button that shows its
description as a form, with Save and Cancel, in place. Edit hides while
the form is open, so the form always opens on the saved description.
Saving posts to /hook/{id}/entrypoints/{entrypointID}/edit, behind the
same login, CSRF and ownership checks as activate, deactivate and
delete, and writes only the description column, so the URL never
changes. An empty description shows as "Entrypoint". Activate and
deactivate now write only the active column, so they cannot write back
an older description over an edit.

Model: opus-5-5

internal/handlers/notice.go

@@ -20,6 +20,7 @@ const (
 	webhookSaved          noticeCode = "webhook-saved"
 	webhookDeleted        noticeCode = "webhook-deleted"
 	entrypointAdded       noticeCode = "entrypoint-added"
+	entrypointSaved       noticeCode = "entrypoint-saved"
 	entrypointDeleted     noticeCode = "entrypoint-deleted"
 	entrypointActivated   noticeCode = "entrypoint-activated"
 	entrypointDeactivated noticeCode = "entrypoint-deactivated"
@@ -48,6 +49,7 @@ func noticeFor(r *http.Request) *notice {
 		webhookSaved:          {Text: "Webhook saved."},
 		webhookDeleted:        {Text: "Webhook deleted."},
 		entrypointAdded:       {Text: "Entrypoint added."},
+		entrypointSaved:       {Text: "Entrypoint description saved."},
 		entrypointDeleted:     {Text: "Entrypoint deleted."},
 		entrypointActivated:   {Text: "Entrypoint activated."},
 		entrypointDeactivated: {Text: "Entrypoint deactivated."},