frontend: RTL sidebar arrow placement + reverse-geocode clinic location

- Arabic RTL: stack the collapse arrow/bell above the nav icons instead of
  pinning them to the opposite edge; mirror the panel-toggle glyph; flip the
  notifications popover to open toward the content side.
- "Use my current location" now reverse-geocodes (OpenStreetMap Nominatim) to
  fill address/city/country, not just latitude/longitude, with a graceful
  coordinates-only fallback. New settings.location.geoPartial key in all 5 locales.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

frontend/lib/i18n/locales/en/translation.json

@@ -2017,7 +2017,8 @@
       "useMyLocation": "Use my current location",
       "locating": "Locating…",
       "geoUnsupported": "Location isn't available on this device.",
-      "geoError": "Couldn't get your location. Check permissions and try again."
+      "geoError": "Couldn't get your location. Check permissions and try again.",
+      "geoPartial": "Filled the coordinates — please add the address details manually."
     },
     "signing": {
       "keyTitle": "Signing key",