feat(events): expose recurrence presets in EventSlideOver

Adds a "Repeat" select (None / Daily / Weekly / Monthly / Yearly) that
reads/writes the existing Event.recurrence RRULE. CalDAV-imported rules
with extra parts (e.g. FREQ=WEEKLY;BYDAY=MO,WE,FR) surface as a disabled
"Custom" option with the raw rule shown read-only — visible but
preserved unless the user explicitly picks a preset to replace it.

EventUpdatePayload.recurrence is now string | null so we can clear via
PATCH; backend service already treats null as "clear" (recurrence is in
the nullable set in update_event).

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

frontend/src/api/client.ts

@@ -545,7 +545,7 @@ export interface EventUpdatePayload {
   description?: string;
   location?: string;
   color?: string;
-  recurrence?: string;
+  recurrence?: string | null;
   project_id?: number;
 }
 

frontend/src/components/EventSlideOver.vue

@@ -37,6 +37,36 @@ const description = ref("");
 const location = ref("");
 const color = ref("");
 const projectId = ref<number | null>(null);
+const recurrence = ref<string>("");
+
+// Preset RRULE strings. The select binds to `recurrencePreset`, which writes
+// through to `recurrence`. CalDAV-imported rules with extra parts
+// (e.g. `FREQ=WEEKLY;BYDAY=MO,WE,FR`) fall through to "custom" and the raw
+// string is shown read-only below the select.
+const RECURRENCE_PRESETS: Record<string, string> = {
+  none: "",
+  daily: "FREQ=DAILY",
+  weekly: "FREQ=WEEKLY",
+  monthly: "FREQ=MONTHLY",
+  yearly: "FREQ=YEARLY",
+};
+
+const recurrencePreset = computed<string>({
+  get() {
+    const r = (recurrence.value || "").trim();
+    if (!r) return "none";
+    for (const [key, val] of Object.entries(RECURRENCE_PRESETS)) {
+      if (val && val === r) return key;
+    }
+    return "custom";
+  },
+  set(key: string) {
+    if (key === "custom") return; // no-op; can't pick custom from dropdown
+    recurrence.value = RECURRENCE_PRESETS[key] ?? "";
+  },
+});
+
+const isCustomRecurrence = computed(() => recurrencePreset.value === "custom");
 
 function dateFromIso(iso: string): string {
   const d = new Date(iso);
@@ -115,6 +145,7 @@ function resetForm() {
     location.value = props.event.location || "";
     color.value = props.event.color || "";
     projectId.value = props.event.project_id;
+    recurrence.value = props.event.recurrence || "";
     _lastDurationMin = !allDay.value && startTime.value && endTime.value ? durationMin(startTime.value, endTime.value) : 60;
     if (_lastDurationMin <= 0) _lastDurationMin = 60;
   } else {
@@ -130,6 +161,7 @@ function resetForm() {
     location.value = "";
     color.value = "";
     projectId.value = null;
+    recurrence.value = "";
     _lastDurationMin = 60;
   }
   deleteConfirm.value = false;
@@ -257,6 +289,7 @@ async function save() {
         location: location.value,
         color: color.value,
         project_id: projectId.value ?? undefined,
+        recurrence: recurrence.value || null,
       };
       const updated = await updateEvent(props.event.id, payload);
       emit("updated", updated);
@@ -270,6 +303,7 @@ async function save() {
         location: location.value,
         color: color.value,
         project_id: projectId.value ?? undefined,
+        recurrence: recurrence.value || undefined,
       };
       const created = await createEvent(payload);
       emit("created", created);
@@ -374,6 +408,24 @@ async function doDelete() {
             </div>
           </div>
 
+          <!-- Recurrence -->
+          <div class="form-field">
+            <label class="form-label">Repeat</label>
+            <select v-model="recurrencePreset" class="form-input">
+              <option value="none">Does not repeat</option>
+              <option value="daily">Daily</option>
+              <option value="weekly">Weekly</option>
+              <option value="monthly">Monthly</option>
+              <option value="yearly">Yearly</option>
+              <option v-if="isCustomRecurrence" value="custom" disabled>Custom</option>
+            </select>
+            <p v-if="isCustomRecurrence" class="recurrence-custom-hint">
+              Custom rule: <code>{{ recurrence }}</code>
+              <br />
+              <span class="form-hint">Picking a preset will replace this rule.</span>
+            </p>
+          </div>
+
           <!-- Location -->
           <div class="form-field">
             <label class="form-label">Location <span class="form-hint">(optional)</span></label>
@@ -539,6 +591,22 @@ async function doDelete() {
   color: var(--color-text-secondary);
 }
 
+.recurrence-custom-hint {
+  margin: 4px 0 0;
+  font-size: 0.75rem;
+  color: var(--color-text-secondary);
+  line-height: 1.4;
+}
+.recurrence-custom-hint code {
+  background: var(--color-input-bg, #111113);
+  border: 1px solid var(--color-border, #2a2b30);
+  border-radius: 4px;
+  padding: 1px 5px;
+  font-family: var(--font-mono, ui-monospace, monospace);
+  font-size: 0.72rem;
+  color: var(--color-text, #e8e9f0);
+}
+
 .toggle-btn {
   background: var(--color-input-bg, #111113);
   border: 1px solid var(--color-border, #2a2b30);