feat(geoportal): building body labels (C1, C2, C3...) on map at zoom 17+

Extracts body suffix from cadastral_ref (e.g. "77102-C1" → "C1") and
displays as centered label on each building polygon. Only visible at
zoom 17+ to avoid clutter at lower zooms.

Applied to both geoportal map-viewer and parcel-sync map tab.
Uses siruta filter in parcel-sync tab.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/modules/parcel-sync/components/tabs/map-tab.tsx

@@ -46,6 +46,7 @@ const BASE_LAYERS = [
   "l-terenuri-label",
   "l-cladiri-fill",
   "l-cladiri-line",
+  "l-cladiri-label",
 ];
 
 /* ------------------------------------------------------------------ */