feat(fhir): wire the German BfArM ATC locale toggle into the export route

The builder already accepts a germanAtc option that appends the BfArM ATC
URI after the WHO entry. Thread it from the health-record export route: an
explicit germanAtc flag on the selection payload wins, otherwise it derives
from a German-region locale. The WHO coding stays coding[0], byte-identical
and locale-independent, so a WHO-only consumer is unaffected.

Add the optional germanAtc field to the strict export selection schema and
regenerate the OpenAPI contract.

src/lib/validations/health-record-export.ts

@@ -97,6 +97,10 @@ export const exportSelectionSchema = z
     practiceName: z.string().max(120).optional(),
     includeCharts: z.boolean().optional(),
     includeAiSummary: z.boolean().optional(),
+    // FHIR only: additionally emit the German BfArM ATC URI alongside the WHO
+    // entry on each medication concept (WHO stays first, byte-identical). When
+    // omitted, the route derives it from a German-region locale.
+    germanAtc: z.boolean().optional(),
   })
   .strict();