Phase 6: fix the live Home Assistant write (Local Calendar, no event id)

The first live run against the new calendar.school entity failed loudly twice,
and both causes are fixed here.

- The Local Calendar rejects `return_response` on calendar.create_event. The
  client retries the call without it and ignores the changed-states array that
  Home Assistant returns instead.
- Home Assistant then reports no event id. The item keeps the description
  marker ([compass-nhs:<id>]) as its reference, so it leaves the candidate set
  and is never written twice. The live retry proved it: both events already in
  the calendar were adopted by their markers, with no duplicate.
- calendar.get_events reports `start` / `end` (a date-time or a bare date), not
  `start_date_time`; the reader now accepts all three shapes.

A model must no longer classify events. The calendar write depends on the
school-event rule, and the LLM labelled every event "normal"; events now keep
the deterministic rule under both classifiers.

Also fix the Phase 5 screenshot script: the calendar banner shares the `.scan`
class, so select each banner by its labelled section.

Docs record the accepted decision: Sam chose a Home Assistant Local Calendar,
so the target is calendar.school.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

scripts/screenshot-phase5.mjs

@@ -97,14 +97,25 @@ try {
     }
   }
 
-  // 4. The scan banner on its own, cropped to the top of the dashboard.
+  // 4. The scan banner on its own, cropped to the top of the dashboard. The
+  //    class is shared with the calendar banner, so select by the labelled
+  //    section, not by `.scan` alone.
   await page.goto(`${BASE}/`, { waitUntil: "networkidle" });
-  await page.waitForSelector(".scan", { timeout: 20000 });
+  const scanBanner = page.locator('.scan[aria-labelledby="scan-title"]');
+  await scanBanner.waitFor({ timeout: 20000 });
   const bannerFile = path.join(OUT, "scan-banner.png");
-  await page.locator(".scan").screenshot({ path: bannerFile });
+  await scanBanner.screenshot({ path: bannerFile });
   shots.push(bannerFile);
   console.log(`shot ${bannerFile}`);
 
+  // 5. The calendar banner (Phase 6, FR-8 / FR-12).
+  const calendarBanner = page.locator('.scan[aria-labelledby="calendar-title"]');
+  await calendarBanner.waitFor({ timeout: 20000 });
+  const calendarFile = path.join(OUT, "calendar-banner.png");
+  await calendarBanner.screenshot({ path: calendarFile });
+  shots.push(calendarFile);
+  console.log(`shot ${calendarFile}`);
+
   await sleep(100);
   console.log(`done: ${shots.length} screenshot(s) in ${OUT}`);
 } finally {