Rebrand: Co-op Check-in -> Co-op Survey in user-facing copy

Updates the tool product name across the app UI (header, page title,
section labels, form buttons, success/error states, report stat labels),
README, deployment docs, and the CiviCRM email template guidance.
Custom domain references move from check-in.fci.coop to survey.fci.coop
(DNS update still required).

The underlying CiviCRM "Check-in (organizing)" activity type, custom
group machine names (Check_in_data__organizing_), health-check ids,
and the internal org_engagement_check_in form id are unchanged --
those are CiviCRM contract surfaces, not product copy.

components/ReportView.tsx

@@ -174,7 +174,7 @@ function ReportContextHeader({
         {currentStageLabel || "—"}
       </p>
       <dl className="mt-5 grid grid-cols-3 gap-3 border-t border-rule-soft pt-4 text-sm sm:gap-6">
-        <Stat label="Check-ins" value={String(totalActivities)} />
+        <Stat label="Surveys" value={String(totalActivities)} />
         <Stat label="Fields tracked" value={String(totalFieldsTracked)} />
         <Stat
           label="Span"
@@ -1414,7 +1414,7 @@ function EmptyState() {
     <div className="rounded-lg border border-dashed border-rule bg-paper-2/30 px-6 py-10 text-center">
       <p className="font-display text-lg text-ink-soft">No entries on file yet.</p>
       <p className="mt-2 text-sm text-ink-mute">
-        Your co-op&apos;s first check-in will appear here once it&apos;s submitted.
+        Your co-op&apos;s first survey will appear here once it&apos;s submitted.
       </p>
     </div>
   );