feat(bp): repositories + identity generation for runtime-inserted tables

Add ValueGeneratedOnAdd to ViewerBattlePassProgress.Id and
ViewerBattlePassClaims.Id so Postgres generates IDENTITY values at
runtime. Regenerate AddBattlePass migration in-place to include the
IdentityByDefaultColumn annotations. Add IBattlePassRepository /
BattlePassRepository (season lookup + level-curve cache) and
IViewerBattlePassRepository / ViewerBattlePassRepository
(get-or-create progress, claim reads/writes).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

SVSim.Database/Repositories/BattlePass/IBattlePassRepository.cs

@@ -0,0 +1,27 @@
+using SVSim.Database.Models;
+
+namespace SVSim.Database.Repositories.BattlePass;
+
+public interface IBattlePassRepository
+{
+    /// <summary>
+    /// Active season for the given moment (StartDate &lt;= when &lt; EndDate). Returns null
+    /// if none. If multiple match (overlap), the most recently started wins.
+    /// </summary>
+    Task<BattlePassSeasonEntry?> GetActiveSeasonAsync(DateTimeOffset when, CancellationToken ct);
+
+    /// <summary>
+    /// Season by id (no time-window filter). Used by /battle_pass/buy to validate request.season_id.
+    /// </summary>
+    Task<BattlePassSeasonEntry?> GetSeasonAsync(int seasonId, CancellationToken ct);
+
+    /// <summary>
+    /// All rewards for a season, both tracks. Sorted by (Track, Level) for deterministic wire order.
+    /// </summary>
+    Task<List<BattlePassRewardEntry>> GetSeasonRewardsAsync(int seasonId, CancellationToken ct);
+
+    /// <summary>
+    /// Global level curve. Cached after first load.
+    /// </summary>
+    Task<IReadOnlyList<BattlePassLevelEntry>> GetLevelCurveAsync(CancellationToken ct);
+}