feat(packs): rewrite PackOpenService against per-pack draw table

Sampler is now driven by PackDrawTable: roll DrawTier per slot by
cumulative slot-rate weights, then pick a card within tier by per-card
weights renormalized within the tier. Rate-less Guaranteed-Leader-Card
rows draw uniform over (pool minus owned), falling back to the full
pool when all are owned. Bonus slot fires once at the end of a 10-pack
open when HasBonusSlot is set.

Slot 8 falls back to the general slot's per-card weights for the rolled
tier when slot-8 has only a rarity-level rate quoted (the common shape
on normal packs).

PackController.Open loads the draw table + viewer owned card ids and
passes them to the sampler; the category-based forced-Legendary slot-8
override is gone. ICardFoilLookup replaces ICardPoolProvider for the
foil-twin heuristic.

Drops the test-fixture pack-draw seed overlay so the production seed
flows through the importer tests; controller tests that fabricate their
own card sets now call factory.SeedPackDrawTableAsync(...) to install a
matching stub draw table.

WeightedPick helper handles the cumulative-band roll for both stages.
Five sampler tests + four WeightedPick tests + five importer/repo
tests; full suite is 653/653 green.

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

SVSim.UnitTests/Controllers/TutorialFlowEndToEndTests.cs

@@ -42,6 +42,8 @@ public class TutorialFlowEndToEndTests
             });
             await db.SaveChangesAsync();
         }
+        // Install a draw table for 99047 pointing at the seeded starter cards.
+        await factory.SeedPackDrawTableAsync(99047, 90001001L, 90001002L, 90001003L);
 
         using var client = factory.CreateAuthenticatedClient(viewerId);