fix(appointment): render real slot structure in time picker

The slots API returns data.sessions[].slots[] with start_time (HH:MM),
is_available, and start/end unix timestamps — not the morning/evening +
time/status shape the UI assumed. Add lib/appointmentSlots.js to flatten
sessions into morning/evening by start_time, fetch with doctor.uuid, and
read item.start_time / item.is_available in the slot grid. Derive the
clinic address from the already-loaded doctor.address by location_id
instead of a separate auth-required call.

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

lib/appointmentSlots.js

@@ -0,0 +1,21 @@
+const MORNING_END = "12:00";
+
+export function adaptSlots(slotsResponse) {
+  const sessions = slotsResponse?.data?.sessions ?? slotsResponse?.sessions ?? [];
+
+  const morning = [];
+  const evening = [];
+
+  sessions.forEach((session) => {
+    (session.slots ?? []).forEach((slot) => {
+      const target = slot.start_time < MORNING_END ? morning : evening;
+      target.push(slot);
+    });
+  });
+
+  return { morning, evening };
+}
+
+export function hasAvailable(slots) {
+  return Array.isArray(slots) && slots.some((slot) => slot.is_available);
+}