Add birthday feature (iOS)

- LocalCalendar/CalEvent gain is_birthday + birthday fields; API sends
  rrule/external_uid/birth_year and can create/update birthday calendars
- BirthdaysImporter: mirrors Contacts birthdays into a chosen birthday
  calendar, reconciling by external_uid (leaves manual entries untouched)
- AccountsView: "birthday calendar" toggle + notify-days when creating a
  calendar, and a "Birthdays from Contacts" section (enable + target + sync now)
- FAB long-press menu -> "New birthday" opens a minimal name+date mask
  (BirthdayEditorSheet) targeting birthday calendars, with year-unknown option
- Event bars render display_title (age) and a cake icon via EventLabel
- NSContactsUsageDescription added to both app build configs

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Calendarr iOS/Views/Calendar/BirthdayEditorSheet.swift

@@ -0,0 +1,104 @@
+import SwiftUI
+
+/// Minimal "new birthday" mask: pick a birthday calendar, enter a name and a
+/// date (day + month, optionally a year). Saves an all-day, yearly-recurring
+/// local event; the server adds the age suffix and cake icon on read.
+struct BirthdayEditorSheet: View {
+    let api: CalendarrAPI
+    var onDone: () async -> Void
+
+    @AppStorage("appLanguage") private var appLang = "system"
+    @Environment(\.dismiss) private var dismiss
+
+    @State private var calendars: [LocalCalendar] = []
+    @State private var selectedCalId: Int? = nil
+    @State private var name = ""
+    @State private var date = Date()
+    @State private var yearUnknown = false
+    @State private var loading = true
+    @State private var saving = false
+
+    private var birthdayCalendars: [LocalCalendar] {
+        calendars.filter { $0.isBirthday && ($0.owned || $0.permission == "read_write") }
+    }
+
+    private var canSave: Bool {
+        !saving && selectedCalId != nil
+            && !name.trimmingCharacters(in: .whitespaces).isEmpty
+    }
+
+    var body: some View {
+        NavigationStack {
+            Form {
+                if loading {
+                    HStack { Spacer(); ProgressView(); Spacer() }
+                } else if birthdayCalendars.isEmpty {
+                    Text(L10n.t("birthday.no_calendars", appLang))
+                        .foregroundStyle(.secondary)
+                } else {
+                    Section(L10n.t("birthday.person", appLang)) {
+                        TextField(L10n.t("birthday.person_placeholder", appLang), text: $name)
+                    }
+                    Section(L10n.t("birthday.date", appLang)) {
+                        DatePicker(L10n.t("birthday.date", appLang), selection: $date,
+                                   displayedComponents: [.date])
+                        Toggle(L10n.t("birthday.year_unknown", appLang), isOn: $yearUnknown)
+                    }
+                    if birthdayCalendars.count > 1 {
+                        Section(L10n.t("birthday.contacts.target", appLang)) {
+                            Picker(L10n.t("birthday.contacts.target", appLang), selection: $selectedCalId) {
+                                ForEach(birthdayCalendars) { c in
+                                    Text(c.name).tag(Optional(c.id))
+                                }
+                            }
+                        }
+                    }
+                }
+            }
+            .navigationTitle(L10n.t("birthday.new", appLang))
+            .navigationBarTitleDisplayMode(.inline)
+            .toolbar {
+                ToolbarItem(placement: .cancellationAction) {
+                    Button(L10n.t("common.cancel", appLang)) { dismiss() }
+                }
+                ToolbarItem(placement: .confirmationAction) {
+                    Button(L10n.t("event.save", appLang)) { Task { await save() } }
+                        .disabled(!canSave)
+                }
+            }
+            .task { await load() }
+        }
+    }
+
+    private func load() async {
+        calendars = (try? await api.getLocalCalendars()) ?? []
+        if selectedCalId == nil { selectedCalId = birthdayCalendars.first?.id }
+        loading = false
+    }
+
+    private func save() async {
+        guard let calId = selectedCalId else { return }
+        saving = true
+        let cal = Calendar.current
+        let comps = cal.dateComponents([.year, .month, .day], from: date)
+        let month = comps.month ?? 1
+        let day = comps.day ?? 1
+        let year = yearUnknown ? nil : comps.year
+        // All-day anchor at local noon; anchor year = birth year (else 1970) so
+        // the yearly rule expands across any queried range.
+        var anchor = DateComponents()
+        anchor.year = year ?? 1970
+        anchor.month = month
+        anchor.day = day
+        anchor.hour = 12
+        let start = cal.date(from: anchor) ?? date
+        let end = cal.date(byAdding: .day, value: 1, to: start) ?? start
+        _ = try? await api.createLocalEvent(
+            calendarId: calId, title: name.trimmingCharacters(in: .whitespaces),
+            start: start, end: end, isAllDay: true, location: "", description: "",
+            color: nil, rrule: "FREQ=YEARLY", birthYear: year
+        )
+        await onDone()
+        dismiss()
+    }
+}