feat: show 'Request signatures' button only for draft signers in appropriate order

The 'Request signatures' button now appears conditionally based on signing flow:

- Parallel flow: Shows when any signer has DRAFT status (status === 0)
- Sequential flow: Shows only when current signing order has draft signers
  - Finds the lowest pending order among unsigned signers
  - Checks if that order contains any draft signers

This prevents requesting signatures from signers who aren't in their turn yet
in sequential signing, while maintaining flexibility in parallel signing.

Refactored logic into smaller, focused methods:
- hasAnyDraftSigner: Checks for any draft signer (parallel mode)
- hasSequentialDraftSigners: Orchestrates sequential mode verification
- getCurrentSigningOrder: Gets current order that should sign
- hasOrderDraftSigners: Checks if specific order has draft signers

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

Author: vitormattos

src/Components/RightSidebar/RequestSignatureTab.vue

@@ -311,7 +311,17 @@ export default {
 			if (!this.filesStore.canSave()) {
 				return false
 			}
-			return this.hasSigners
+			return this.hasDraftSigners
+		},
+		hasDraftSigners() {
+			const file = this.filesStore.getFile()
+			if (!file?.signers) {
+				return false
+			}
+
+			return this.isOrderedNumeric
+				? this.hasSequentialDraftSigners(file)
+				: this.hasAnyDraftSigner(file)
 		},
 		hasSigners() {
 			return this.filesStore.hasSigners(this.filesStore.getFile())
@@ -379,6 +389,27 @@ export default {
 
 			return !hasPendingLowerOrder
 		},
+		hasAnyDraftSigner(file) {
+			return file.signers.some(signer => signer.status === 0)
+		},
+		hasSequentialDraftSigners(file) {
+			const signersNotSigned = file.signers.filter(s => !s.signed)
+			if (signersNotSigned.length === 0) {
+				return false
+			}
+
+			const currentOrder = this.getCurrentSigningOrder(signersNotSigned)
+			return this.hasOrderDraftSigners(file, currentOrder)
+		},
+		getCurrentSigningOrder(signersNotSigned) {
+			return Math.min(...signersNotSigned.map(s => s.signingOrder || 1))
+		},
+		hasOrderDraftSigners(file, order) {
+			return file.signers.some(signer => {
+				const signerOrder = signer.signingOrder || 1
+				return signerOrder === order && signer.status === 0
+			})
+		},
 		enabledMethods() {
 			return this.methods.filter(method => method.enabled)
 		},