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
 

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

@@ -69,9 +69,27 @@ public class ProfileService
         if (patch.TryGetProperty("socialsVisibility", out var sv) && sv.ValueKind == JsonValueKind.String) p.SocialsVisibility = sv.GetString()!;
         if (patch.TryGetProperty("socials", out var so) && so.ValueKind == JsonValueKind.Object)
             p.Socials = JsonSerializer.Deserialize<SocialLinksDto>(so.GetRawText(), JsonOpts.Default) ?? p.Socials;
-        return await Save(p);
+        // One-time "set your city" reward: first non-empty city → +500 coins.
+        var cityRewarded = false;
+        if (patch.TryGetProperty("city", out var ci) && ci.ValueKind == JsonValueKind.String)
+        {
+            var city = ci.GetString();
+            p.City = city;
+            if (!string.IsNullOrWhiteSpace(city) && !p.CityRewardClaimed)
+            {
+                p.CityRewardClaimed = true;
+                p.Coins += CityReward;
+                cityRewarded = true;
+            }
+        }
+        await Save(p);
+        if (cityRewarded) await Ledger(uid, "city", CityReward, "profile-city");
+        return p;
     }
 
+    /// <summary>One-time coin reward for setting your city (mirrors client CITY_REWARD).</summary>
+    public const int CityReward = 500;
+
     public async Task<ProfileDto> UpgradePlan(string uid)
     {
         var p = await GetOrCreate(uid, null);