feat(arena-colosseum): 2-pick + curated deck sources (phase 3)

Closes the family. arena-colosseum 10/16 → 15/16 zero stubs (the 16th —
finish_load — is dead per project_dead_battle_endpoints).

* 2-Pick draft lift onto ArenaColosseumController:
  - get_candidate_classes samples from ArenaTwoPickConfig.AllowedClassIds
    and persists the slate onto the run.
  - class_choose accepts class_id XOR chaos_id; both populate run.ClassId,
    chaos branch stores ChaosId for replay.
  - get_candidate_cards is the idempotent draft-resume snapshot.
  - card_choose appends both cards from the picked pair, advances turn 1..15.
  - Pool override: ArenaTwoPickCardPoolService gets a non-breaking
    GeneratePickSetsForTurn(..., poolCardSetIds) overload; Colosseum routes
    pass ColosseumSeasonConfig.PoolCardSetIds (falls back to challenge →
    rotation when empty).
* Curated-deck schema: ColosseumHofDeck / ColosseumWindFallDeck /
  ColosseumAvatarDeck — three identical tables (separate per per-pool
  operational lifecycle), unique on DeckNo. Migration AddColosseumCuratedDecks.
* IColosseumCuratedDeck interface + a generic ColosseumCuratedDeckImporterBase<T>
  with three concrete subclasses (HOF / WindFall / Avatar), registered in
  Bootstrap. Seed files ship empty.
* 6 curated endpoints on ArenaColosseumController: get_{hof|windfall|avatar}_deck_list
  return BARE-ARRAY data per spec; register_{hof|windfall|avatar}_deck share
  one generic RegisterCuratedAsync<T> dispatcher. Cross-pool register
  rejected via per-pool lookup. Curated register has no is_published flag
  (constructed-only) — clears the run's flag for state consistency.
* Tests: 5 draft HTTP tests + 11 curated-deck HTTP tests (4 parameterized
  3 ways across HOF/WindFall/Avatar + a cross-pool isolation test + an
  is_published clear test). Existing TwoPick service tests updated for the
  new pool overload. Full suite: 1347/1347.

Phase 3 ship gate met. Branch ready for merge.

SVSim.Database/Migrations/SVSimDbContextModelSnapshot.cs

@@ -970,6 +970,41 @@ namespace SVSim.Database.Migrations
                     b.ToTable("ClassExpCurve");
                 });
 
+            modelBuilder.Entity("SVSim.Database.Models.ColosseumAvatarDeck", b =>
+                {
+                    b.Property<long>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("bigint");
+
+                    NpgsqlPropertyBuilderExtensions.UseIdentityByDefaultColumn(b.Property<long>("Id"));
+
+                    b.Property<string>("CardListJson")
+                        .IsRequired()
+                        .HasColumnType("jsonb");
+
+                    b.Property<int>("ClassId")
+                        .HasColumnType("integer");
+
+                    b.Property<int>("DeckNo")
+                        .HasColumnType("integer");
+
+                    b.Property<int>("DisplayOrder")
+                        .HasColumnType("integer");
+
+                    b.Property<long>("LeaderSkinId")
+                        .HasColumnType("bigint");
+
+                    b.Property<long>("SleeveId")
+                        .HasColumnType("bigint");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("DeckNo")
+                        .IsUnique();
+
+                    b.ToTable("ColosseumAvatarDecks");
+                });
+
             modelBuilder.Entity("SVSim.Database.Models.ColosseumConfig", b =>
                 {
                     b.Property<int>("Id")
@@ -1041,6 +1076,76 @@ namespace SVSim.Database.Migrations
                     b.ToTable("Colosseums");
                 });
 
+            modelBuilder.Entity("SVSim.Database.Models.ColosseumHofDeck", b =>
+                {
+                    b.Property<long>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("bigint");
+
+                    NpgsqlPropertyBuilderExtensions.UseIdentityByDefaultColumn(b.Property<long>("Id"));
+
+                    b.Property<string>("CardListJson")
+                        .IsRequired()
+                        .HasColumnType("jsonb");
+
+                    b.Property<int>("ClassId")
+                        .HasColumnType("integer");
+
+                    b.Property<int>("DeckNo")
+                        .HasColumnType("integer");
+
+                    b.Property<int>("DisplayOrder")
+                        .HasColumnType("integer");
+
+                    b.Property<long>("LeaderSkinId")
+                        .HasColumnType("bigint");
+
+                    b.Property<long>("SleeveId")
+                        .HasColumnType("bigint");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("DeckNo")
+                        .IsUnique();
+
+                    b.ToTable("ColosseumHofDecks");
+                });
+
+            modelBuilder.Entity("SVSim.Database.Models.ColosseumWindFallDeck", b =>
+                {
+                    b.Property<long>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("bigint");
+
+                    NpgsqlPropertyBuilderExtensions.UseIdentityByDefaultColumn(b.Property<long>("Id"));
+
+                    b.Property<string>("CardListJson")
+                        .IsRequired()
+                        .HasColumnType("jsonb");
+
+                    b.Property<int>("ClassId")
+                        .HasColumnType("integer");
+
+                    b.Property<int>("DeckNo")
+                        .HasColumnType("integer");
+
+                    b.Property<int>("DisplayOrder")
+                        .HasColumnType("integer");
+
+                    b.Property<long>("LeaderSkinId")
+                        .HasColumnType("bigint");
+
+                    b.Property<long>("SleeveId")
+                        .HasColumnType("bigint");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("DeckNo")
+                        .IsUnique();
+
+                    b.ToTable("ColosseumWindFallDecks");
+                });
+
             modelBuilder.Entity("SVSim.Database.Models.DailyLoginBonusEntry", b =>
                 {
                     b.Property<int>("Id")