feat(profile): "set your city" gamification box → one-time 500-coin reward

- New searchable city picker (src/lib/iran-cities.ts, ~60 Iranian cities,
  fa/en search) shown as a gold reward card at the top of the profile Basic tab.
- First time a non-empty city is set, the player earns 500 coins (CITY_REWARD),
  granted server-authoritatively. Collapses to a compact summary afterwards with
  a "change city" option (no re-reward).
- Frontend: UserProfile.city + cityRewardClaimed; mock-service grants on first
  set; session/service updateProfile accept `city`; celebratory toast + sfx.
- Backend (.NET): ProfileDto.City/CityRewardClaimed (JSON blob → no migration);
  ProfileService.Update grants +500 once and writes a "city" ledger entry.
- i18n: city.* keys (fa + en).

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

server/src/Hokm.Server/Profiles/ProfileModels.cs

@@ -59,6 +59,8 @@ public class ProfileDto
 
     // social
     public string Gender { get; set; } = ""; // "" | male | female | other
+    public string? City { get; set; } // selected city id (see client IRAN_CITIES)
+    public bool CityRewardClaimed { get; set; } // one-time "set your city" reward granted
     public SocialLinksDto Socials { get; set; } = new();
     public string SocialsVisibility { get; set; } = "public"; // public | friends | hidden