feat(sharing): add an error boundary to the public share route

A render failure on `/c/<token>` previously fell through to the full-app
error screen, which carries app chrome the public share view never wants.
Add a route-scoped, chrome-free error boundary that shows a localised,
stack-free message and a single retry. Add the matching copy across all
six locales.

src/app/c/error.tsx

@@ -0,0 +1,41 @@
+"use client";
+
+/**
+ * Error boundary for the public clinician share route (`/c/<token>`).
+ *
+ * The share view carries no app chrome and no session, so a render failure must
+ * not fall through to the full-app error screen. This renders a clean, locale-
+ * aware, stack-free message and offers a single retry. No record data, no
+ * digest, no stack — a probe learns nothing from a failed render.
+ */
+import { useTranslations } from "@/lib/i18n/context";
+import { Button } from "@/components/ui/button";
+
+export default function ClinicianShareError({
+  reset,
+}: {
+  error: Error & { digest?: string };
+  reset: () => void;
+}) {
+  const { t } = useTranslations();
+
+  return (
+    <main className="mx-auto flex min-h-screen max-w-md flex-col justify-center px-4">
+      <div className="border-border bg-card space-y-4 rounded-lg border p-6 text-center">
+        <h1 className="text-lg font-semibold">
+          {t("clinicianView.loadError.title")}
+        </h1>
+        <p className="text-muted-foreground text-sm">
+          {t("clinicianView.loadError.description")}
+        </p>
+        <Button
+          onClick={() => reset()}
+          className="min-h-11 w-full sm:min-h-9"
+          variant="outline"
+        >
+          {t("clinicianView.loadError.retry")}
+        </Button>
+      </div>
+    </main>
+  );
+}