feat(packs): add PackDraw* tables and IsEnabled column

Three new EF entities and a migration:
- PackDrawConfigEntry (per-pack: animation rate, has-bonus flag, special-kind label)
- PackDrawSlotRateEntry (pack/slot/tier -> rate, unique index)
- PackDrawCardWeightEntry (per-card-rate facts incl rate-less rows)

DrawSlot {General, Eighth, Bonus} and DrawTier {Bronze, Silver, Gold, Legendary, Special}.
Special collapses leader_card and limited_time_leader (verified mutually exclusive per pack).

IsEnabled column on PackConfigEntry — admin gate for synthesized stubs, distinct from
the wire-mirror IsHide.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

SVSim.Database/Models/PackDrawConfigEntry.cs

@@ -0,0 +1,16 @@
+using SVSim.Database.Common;
+
+namespace SVSim.Database.Models;
+
+/// <summary>
+/// One row per pack covered by drawrates data. PK is the pack id (matches PackConfigEntry.Id
+/// for live-capture rows; standalone for archive-only packs). Weak relationship — PackDraw rows
+/// exist for all archived packs even when no PackConfigEntry is enabled.
+/// </summary>
+public class PackDrawConfigEntry : BaseEntity<int>
+{
+    public double AnimationRatePct { get; set; }
+    public bool HasBonusSlot { get; set; }
+    public string? SpecialKind { get; set; }
+    public string? ShortCode { get; set; }
+}