Let each workflow watch the due date or the start date

Deck 1.18 added a start date to cards (Card::$startdate), so a workflow
no longer has to mean "overdue". Each rule now carries a date_field
('due' | 'start'), chosen in the settings form next to board and stacks.

Existing rules keep the due date: the new column's default supplies it
for every stored row, so there is no backfill step, and
Workflow::getDateFieldOrDue() covers entities that were never near the
database as well as hand-edited values. The controller is the one place
that rejects an unknown value instead of normalising it - a client
asking for a rule it would not get should hear about it.

The probe for the field is property_exists(), not method_exists():
Deck's entities declare no getter as real code - getStartdate(),
getDuedate(), even getId() all go through Entity::__call(), which
method_exists() ignores by definition. A method_exists() guard would
have been false on every Deck version and would have turned every
start-date rule into a silent no-op.

assertDeckAvailable() now also refuses Deck older than 1.18.0. That
floor cannot live in appinfo/info.xml - neither the server's nor the app
store's schema has an app-to-app dependency element - but
<nextcloud min-version="34"> already implies it, since 1.18.x is the
only Deck release line published for Nextcloud 34.

isOverdue() becomes hasPassed(): one function for both dates, since the
comparison and the argument against Deck's day-truncating
getDaysUntilDue() are identical for either.

Also carries a pending NcSelect icon-alignment fix that was already in
the working tree.

Bump to 34.1.0.

src/PersonalSettings.vue

@@ -1,7 +1,7 @@
 <template>
 	<NcSettingsSection
 		name="Deck Workflow-Automatisierung"
-		description="Verschiebt überfällige Karten aus einem Deck-Stapel automatisch in einen anderen Stapel. Ein Hintergrundjob prüft die Regeln alle paar Minuten.">
+		description="Verschiebt Karten automatisch aus einem Deck-Stapel in einen anderen, sobald ihr Fälligkeits- oder Startdatum erreicht ist. Ein Hintergrundjob prüft die Regeln alle paar Minuten.">
 		<NcNoteCard v-if="loadError" type="error">
 			{{ loadError }}
 		</NcNoteCard>
@@ -17,6 +17,7 @@
 						<th>Titel</th>
 						<th>Von Stapel</th>
 						<th>Nach Stapel</th>
+						<th>Auslöser</th>
 						<th>Filter</th>
 						<th>E-Mail</th>
 						<th>Aktiv</th>
@@ -33,6 +34,7 @@
 						</td>
 						<td>{{ stackLabel(workflow.boardId, workflow.sourceStackId) }}</td>
 						<td>{{ stackLabel(workflow.boardId, workflow.targetStackId) }}</td>
+						<td>{{ dateFieldLabel(workflow.dateField) }}</td>
 						<td>
 							<span v-if="!workflow.filterUserIds.length && !workflow.filterLabelIds.length">–</span>
 							<span v-else>
@@ -92,6 +94,34 @@
 					:disabled="!form.boardId"
 					placeholder="Ziel-Stapel wählen" />
 
+				<fieldset class="wfda-fieldset">
+					<legend>Auslösendes Datum</legend>
+					<!--
+						v-model + value + type="radio" + a shared name is the
+						@nextcloud/vue 9 radio API: v-model carries the group's
+						current value, value the one this button stands for. Do
+						not reach for :checked.sync here - Vue 3 dropped .sync,
+						and it would silently never update.
+					-->
+					<NcCheckboxRadioSwitch
+						v-model="form.dateField"
+						value="due"
+						name="wfda-date-field"
+						type="radio">
+						Fälligkeitsdatum überschritten
+					</NcCheckboxRadioSwitch>
+					<NcCheckboxRadioSwitch
+						v-model="form.dateField"
+						value="start"
+						name="wfda-date-field"
+						type="radio">
+						Startdatum erreicht
+					</NcCheckboxRadioSwitch>
+					<p class="wfda-hint">
+						Karten ohne das gewählte Datum werden nie verschoben.
+					</p>
+				</fieldset>
+
 				<NcSelect
 					v-model="form.filterUserIds"
 					input-label="Nur für zugewiesene Benutzer (optional)"
@@ -257,11 +287,16 @@ function emptyForm() {
 		targetStackId: null,
 		filterUserIds: [],
 		filterLabelIds: [],
+		dateField: 'due',
 		notifyEmail: false,
 		enabled: true,
 	}
 }
 
+function dateFieldLabel(dateField) {
+	return dateField === 'start' ? 'Startdatum' : 'Fälligkeit'
+}
+
 function stackLabel(boardId, stackId) {
 	const stacks = stacksByBoard[boardId]
 	if (!stacks) {
@@ -386,6 +421,8 @@ async function editWorkflow(workflow) {
 		targetStackId: workflow.targetStackId,
 		filterUserIds: [...workflow.filterUserIds],
 		filterLabelIds: [...workflow.filterLabelIds],
+		// Workflows stored before this field existed come back without it.
+		dateField: workflow.dateField || 'due',
 		notifyEmail: workflow.notifyEmail,
 		enabled: workflow.enabled,
 	})
@@ -498,4 +535,38 @@ onMounted(loadAll)
 	display: flex;
 	gap: 8px;
 }
+
+.wfda-fieldset {
+	display: flex;
+	flex-direction: column;
+	gap: 4px;
+	/* The form already draws its own frame; the browser default would put a
+	   second box around just this group. */
+	border: none;
+	padding: 0;
+	margin: 0;
+}
+
+.wfda-fieldset legend {
+	font-weight: bold;
+	margin-bottom: 4px;
+}
+
+.wfda-hint {
+	color: var(--color-text-maxcontrast);
+	font-size: 0.9em;
+}
+
+/*
+ * NcSelect positions the clear/open icons (.vs__actions) absolutely relative
+ * to the outer .v-select wrapper, while the dropdown menu itself opens
+ * relative to .vs__dropdown-toggle (its $refs.toggle) — normally the same
+ * box, but any width mismatch between the two (e.g. from global Nextcloud
+ * input styles bleeding into the scoped component) shifts the icons off the
+ * visible border of single-value selects like Board/Quell-/Ziel-Stapel.
+ * Anchoring both to .vs__dropdown-toggle keeps them in sync.
+ */
+:deep(.v-select.select:not(.vs--multiple) .vs__dropdown-toggle) {
+	position: relative;
+}
 </style>