Show a compact year-less date in the day bar so it fits small iPhones

The native date input can't be told to drop the year, so a button face
shows e.g. "Jul 10" and the real input sits hidden behind it, still
holding the value and opening the native picker on tap.

src/app.js

@@ -1563,6 +1563,10 @@
     const isToday = ymd(day) === ymd(new Date());
     document.getElementById("day-next").disabled  = isToday;
     document.getElementById("day-today").disabled = isToday;
+    // Year-less date on the picker's face — the year is implicit and the
+    // saved width keeps the bar on one row on small phones.
+    document.getElementById("day-date-face").textContent =
+      day.toLocaleDateString(undefined, { month: "short", day: "numeric" });
     const title = document.getElementById("overview-title");
     if (title) {
       title.textContent = isToday
@@ -2355,6 +2359,17 @@
   dayPicker.value = ymd(new Date());
   dayPicker.addEventListener("change", render);
 
+  // The face opens the hidden input's native picker (iOS 16+ has showPicker;
+  // focus() is the fallback and is what pops the picker on older iOS anyway).
+  document.getElementById("day-date-face").addEventListener("click", () => {
+    try {
+      if (typeof dayPicker.showPicker === "function") dayPicker.showPicker();
+      else dayPicker.focus();
+    } catch {
+      dayPicker.focus();
+    }
+  });
+
   function shiftSelectedDay(days) {
     const d = selectedDay();
     d.setDate(d.getDate() + days);