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/IViewerBattlePassRepository.cs

@@ -0,0 +1,23 @@
+using SVSim.Database.Enums;
+using SVSim.Database.Models;
+
+namespace SVSim.Database.Repositories.BattlePass;
+
+public interface IViewerBattlePassRepository
+{
+    /// <summary>
+    /// Get-or-create progress row for (viewer, season). New rows are added to the change-tracker
+    /// but NOT saved — caller batches with other mutations.
+    /// </summary>
+    Task<ViewerBattlePassProgressEntry> GetOrCreateProgressAsync(long viewerId, int seasonId, CancellationToken ct);
+
+    /// <summary>
+    /// All claim rows for (viewer, season). Used by /battle_pass/info to enrich is_received.
+    /// </summary>
+    Task<List<ViewerBattlePassClaimEntry>> GetClaimsAsync(long viewerId, int seasonId, CancellationToken ct);
+
+    /// <summary>
+    /// Append a claim row (in-memory; caller saves).
+    /// </summary>
+    void AddClaim(long viewerId, int seasonId, BattlePassTrack track, int level, DateTimeOffset claimedAt);
+}