feat(signature-stamp): implement index behavior

Signed-off-by: Vitor Mattos <1079143+vitormattos@users.noreply.github.com>

Author: vitormattos

src/views/Settings/PolicyWorkbench/settings/signature-stamp/index.ts

@@ -0,0 +1,38 @@
+/**
+ * SPDX-FileCopyrightText: 2026 LibreCode coop and LibreCode contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+
+import { t } from '@nextcloud/l10n'
+
+import SignatureStampRuleEditor from './SignatureStampRuleEditor.vue'
+import type { PolicySettingDefinition } from '../../types'
+
+export const signatureStampDefinition: PolicySettingDefinition<'signature_stamp'> = {
+	key: 'signature_stamp',
+	title: t('libresign', 'Signature stamp'),
+	description: t('libresign', 'Manage the visible signature block, template and dimensions with a richer policy model.'),
+	menuHint: t('libresign', 'Complex policy example with dimensions, render modes, template text, and background behavior.'),
+	editor: SignatureStampRuleEditor,
+	createEmptyValue: () => ({
+		enabled: true,
+		renderMode: 'GRAPHIC_AND_DESCRIPTION',
+		template: '{{ signer_name }} - {{ signed_at }}',
+		templateFontSize: 10,
+		signatureFontSize: 20,
+		signatureWidth: 180,
+		signatureHeight: 70,
+		backgroundMode: 'default',
+		showSigningDate: true,
+	}),
+	summarizeValue: (value) => {
+		if (!value.enabled) {
+			return t('libresign', 'Disabled')
+		}
+
+		return `${value.renderMode} - ${value.signatureWidth}x${value.signatureHeight}`
+	},
+	formatAllowOverride: (allowChildOverride) => allowChildOverride
+		? t('libresign', 'Lower layers may override this rule')
+		: t('libresign', 'Lower layers must inherit this value'),
+}