#485 Fix overlapping layout in the Postpone meeting dialog

In Arabic/RTL the Postpone dialog (opened from the upcoming-meeting
alert) was visibly overlapping its own borders on two tabs:
1. Postpone tab → cascade preview ("الاجتماعات المتأثرة"): the times
   column ran wider than the pink panel, the title column pushed it
   off-screen, and the meeting-# header wrapped to two lines while
   the others stayed on one.
2. Reschedule tab: three native date / start / end inputs forced into
   md:grid-cols-3 inside an sm:max-w-md dialog, which clipped the
   right-most input against the dialog frame in RTL.

Both issues were pure layout — the dialog was simply too narrow for
its content.

Changes (artifacts/tx-os/src/components/executive-meetings/upcoming-meeting-alert.tsx):
- Bumped the postpone DialogContent from `sm:max-w-md` (≈448 px) to
  `sm:max-w-2xl` (≈672 px). Still full width on phones, capped on
  desktop. Reschedule's existing `grid-cols-1 sm:grid-cols-2
  md:grid-cols-3` now has room to actually render three inputs at md
  without clipping (Input already defaults to w-full).
- CascadePromptBlock affected-meetings table: switched to
  `table-fixed` with an explicit `<colgroup>` (w-20 number / flex
  title / w-40 times). The number column was bumped from w-12 to
  w-20 so the Arabic header "رقم الاجتماع" + `whitespace-nowrap`
  has room at common font sizes (raised during code review). Title
  cell keeps its `truncate` + `title=` tooltip but no longer needs
  `max-w-[180px]`. Added `whitespace-nowrap` to # and times headers
  so the latter never wraps. Wrapper got `overflow-x-hidden` to
  belt-and-suspenders the no-horizontal-scroll guarantee. Action
  button row already used `flex-wrap` — preserved.

Tests (artifacts/tx-os/tests/executive-meetings-upcoming-alert.spec.mjs):
- Added a Reschedule-tab regression test that opens the dialog at
  1280×800 in Arabic and asserts the bounding boxes of
  `reschedule-date` / `reschedule-start` / `reschedule-end` all sit
  inside the dialog's bounding box (1 px tolerance).
- Added a Cascade-table regression test (raised during code review)
  that seeds a primary + 2 followers, postpones to fire the cascade
  prompt, and asserts the `cascade-followers-list` and the last
  `<td>` (times) of the first follower row both sit inside the
  dialog at desktop width in RTL.
- Confirmed no behavior regressions across the postpone-by-10,
  cascade follower display, tab-switching, and reschedule-to-tomorrow
  tests.

Out of scope (per task spec): backend cascade/postpone logic, the
floating alert panel itself, dialog visual restyling, and the Cancel
tab beyond what comes "for free" with the wider dialog.

The pre-existing `test` workflow failures (executive-meetings reorder,
font-settings roundtrip, notes-share recipient PATCH 403/404) are
unrelated to this layout change and were already failing before.

artifacts/tx-os/src/components/executive-meetings/upcoming-meeting-alert.tsx

@@ -958,7 +958,10 @@ function CascadePromptBlock({
               ellipsis instead of pushing the times off-screen, and
               the From → To column always fits on one line. */}
           <colgroup>
-            <col className="w-12" />
+            {/* w-20 leaves room for the Arabic header "رقم الاجتماع"
+                with whitespace-nowrap; w-12 was too tight at common
+                font sizes. */}
+            <col className="w-20" />
             <col />
             <col className="w-40" />
           </colgroup>

artifacts/tx-os/tests/executive-meetings-upcoming-alert.spec.mjs

@@ -1291,6 +1291,84 @@ test("Upcoming-meeting alert: details panel renders attendees as numbered tables
   await expect(secondGroupRows.first()).toContainText("Internal One");
 });
 
+test("Postpone dialog: cascade-followers table sits fully inside the dialog (no horizontal spill, RTL)", async ({
+  page,
+}) => {
+  // #485: regression for the cascade preview overlapping the dialog
+  // edge in Arabic. Seed a primary meeting + two followers later in
+  // the same day so the cascade prompt definitely fires after
+  // confirming a postpone, then assert the followers-list bounding
+  // box sits within the dialog's bounding box.
+  await setLang(page, "ar");
+  const primary = await insertImminentMeeting({
+    titleAr: `${TEST_TAG} cascade-layout primary AR ${"بعنوان طويل جداً يكفي لاختبار القص بالنقاط في عمود العنوان داخل اللوحة"}`,
+    titleEn: `${TEST_TAG} cascade-layout primary EN with a sufficiently long title to verify column truncation`,
+    deltaMins: 3,
+  });
+  await insertImminentMeeting({
+    titleAr: `${TEST_TAG} cascade-layout follower-1 AR`,
+    titleEn: `${TEST_TAG} cascade-layout follower-1 EN`,
+    deltaMins: 30,
+  });
+  await insertImminentMeeting({
+    titleAr: `${TEST_TAG} cascade-layout follower-2 AR`,
+    titleEn: `${TEST_TAG} cascade-layout follower-2 EN`,
+    deltaMins: 60,
+  });
+  await page.setViewportSize({ width: 1280, height: 800 });
+  await loginViaUi(page, "admin", "admin123");
+  await page.goto("/");
+  await expect(page.getByTestId("upcoming-meeting-alert")).toBeVisible({
+    timeout: 15_000,
+  });
+  await page.getByTestId("alert-postpone").click();
+  const dialog = page.getByTestId("postpone-dialog");
+  await expect(dialog).toBeVisible();
+  await page.getByTestId("postpone-chip-10").click();
+  await expect(page.getByTestId("postpone-confirm-block")).toBeVisible();
+  await page.getByTestId("postpone-confirm-yes").click();
+
+  // Cascade prompt must appear with this seeding (two later meetings
+  // on the same day). Geometry checks then verify no spill.
+  const followersList = page.getByTestId("cascade-followers-list");
+  await expect(followersList).toBeVisible({ timeout: 8_000 });
+
+  const dialogBox = await dialog.boundingBox();
+  const tableBox = await followersList.boundingBox();
+  expect(dialogBox).not.toBeNull();
+  expect(tableBox).not.toBeNull();
+  // Table must sit fully inside the dialog (1px tolerance for
+  // sub-pixel rounding).
+  expect(tableBox.x + 1).toBeGreaterThanOrEqual(dialogBox.x);
+  expect(tableBox.x + tableBox.width).toBeLessThanOrEqual(
+    dialogBox.x + dialogBox.width + 1,
+  );
+
+  // The truncating title cell must not push the times column out of
+  // the dialog. Check the first follower row's last cell (times).
+  const lastCell = page
+    .locator('[data-testid^="cascade-follower-"]')
+    .first()
+    .locator("td")
+    .last();
+  const lastBox = await lastCell.boundingBox();
+  expect(lastBox).not.toBeNull();
+  expect(lastBox.x + lastBox.width).toBeLessThanOrEqual(
+    dialogBox.x + dialogBox.width + 1,
+  );
+
+  // Politely back out so this seeded meeting doesn't preempt later
+  // tests' alerts.
+  await page.getByTestId("cascade-back").click();
+  await pool.query(
+    `UPDATE executive_meetings
+        SET start_time = (start_time::time + interval '2 hours')::time,
+            end_time   = (end_time::time   + interval '2 hours')::time
+      WHERE id = $1`,
+    [primary.id],
+  );
+});
+
 test("Postpone dialog: reschedule date / start / end inputs sit fully inside the dialog (no clipping at desktop width, RTL)", async ({
   page,
 }) => {