fix: add ordering validation for signature request actions

In ordered numeric signing flow, the frontend now validates that
all lower-order signers have signed before showing 'Request signature'
or 'Send reminder' buttons for higher-order signers.

Changes:
- Extract duplicate ordering validation logic into shared method
  canSignerActInOrder
- Apply ordering validation to both canRequestSignature and
  canSendReminder computed properties
- Move canSignerActInOrder to methods section (takes parameter)

This prevents users from requesting signatures or sending reminders
to signers out of turn when sequential signing is enabled.

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

src/Components/RightSidebar/RequestSignatureTab.vue

@@ -263,20 +263,28 @@ export default {
 		},
 		canRequestSignature() {
 			return (signer) => {
-				return this.filesStore.canRequestSign
-					&& !signer.signed
-					&& signer.signRequestId
-					&& !signer.me
-					&& signer.status === 0
+				if (!this.filesStore.canRequestSign
+					|| signer.signed
+					|| !signer.signRequestId
+					|| signer.me
+					|| signer.status !== 0) {
+					return false
+				}
+
+				return this.canSignerActInOrder(signer)
 			}
 		},
 		canSendReminder() {
 			return (signer) => {
-				return this.filesStore.canRequestSign
-					&& !signer.signed
-					&& signer.signRequestId
-					&& !signer.me
-					&& signer.status === 1
+				if (!this.filesStore.canRequestSign
+					|| signer.signed
+					|| !signer.signRequestId
+					|| signer.me
+					|| signer.status !== 1) {
+					return false
+				}
+
+				return this.canSignerActInOrder(signer)
 			}
 		},
 		showSaveButton() {
@@ -353,6 +361,21 @@ export default {
 		getSvgIcon(name) {
 			return iconMap[`svg${name.charAt(0).toUpperCase() + name.slice(1)}`] || iconMap.svgAccount
 		},
+		canSignerActInOrder(signer) {
+			if (!this.isOrderedNumeric) {
+				return true
+			}
+
+			const file = this.filesStore.getFile()
+			const signerOrder = signer.signingOrder || 1
+
+			const hasPendingLowerOrder = file.signers.some(s => {
+				const otherOrder = s.signingOrder || 1
+				return otherOrder < signerOrder && !s.signed
+			})
+
+			return !hasPendingLowerOrder
+		},
 		enabledMethods() {
 			return this.methods.filter(method => method.enabled)
 		},
@@ -473,7 +496,6 @@ export default {
 				await this.filesStore.updateSignatureRequest({
 					visibleElements: [],
 					signers,
-					status: 1,
 				})
 				showSuccess(t('libresign', 'Signature requested'))
 			} catch (error) {