feat(deck-builder): /deck_code mint + /deck resolve with 3-min in-memory TTL

Adds the portal pair (shadowverse-portal.com deck-builder endpoints) as
anonymous routes on the app server. The translation middleware learns a new
[NoWireEncryption] attribute that skips both AES calls but keeps the rest of
the msgpack + base64 + envelope pipeline intact, matching prod's portal wire
profile observed in data_dumps/traffic_prod_deckcode.ndjson.

Storage is a 3-minute IMemoryCache — codes are anonymous-global, 4-char
lowercase alphanumeric (matches the shortest prod sample). Foil bit is
stripped on mint to match prod's normalize-on-encode behaviour.

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

SVSim.UnitTests/Services/DeckCodeServiceTests.cs

@@ -0,0 +1,56 @@
+using Microsoft.Extensions.Caching.Memory;
+using SVSim.EmulatedEntrypoint.Models.Dtos.Responses.DeckBuilder;
+using SVSim.EmulatedEntrypoint.Services;
+
+namespace SVSim.UnitTests.Services;
+
+public class DeckCodeServiceTests
+{
+    private static DeckCodeService NewService(out IMemoryCache cache, IRandom? random = null)
+    {
+        cache = new MemoryCache(new MemoryCacheOptions());
+        return new DeckCodeService(cache, random ?? new SystemRandom());
+    }
+
+    [Test]
+    public void Mint_returns_4char_lowercase_alphanumeric_code()
+    {
+        var svc = NewService(out _);
+
+        var code = svc.Mint(new DeckPayload { Clan = "1", CardID = new() { 100211010 } });
+
+        Assert.That(code, Has.Length.EqualTo(4));
+        Assert.That(code, Does.Match("^[a-z0-9]+$"));
+    }
+
+    [Test]
+    public void Resolve_returns_payload_when_code_unexpired()
+    {
+        var svc = NewService(out _);
+        var original = new DeckPayload { Clan = "4", CardID = new() { 100414020, 100414020 } };
+
+        var code = svc.Mint(original);
+        var resolved = svc.TryResolve(code);
+
+        Assert.That(resolved, Is.SameAs(original));
+    }
+
+    [Test]
+    public void Resolve_returns_null_for_unknown_code()
+    {
+        var svc = NewService(out _);
+
+        Assert.That(svc.TryResolve("nope"), Is.Null);
+    }
+
+    [Test]
+    public void Resolve_returns_null_after_cache_eviction()
+    {
+        // Don't sleep for the 3-minute TTL — drop the entry directly to simulate expiry.
+        var svc = NewService(out var cache);
+        var code = svc.Mint(new DeckPayload { Clan = "1", CardID = new() { 100211010 } });
+        cache.Remove(DeckCodeService.CacheKey(code));
+
+        Assert.That(svc.TryResolve(code), Is.Null);
+    }
+}