NEO-70: Emit explicit nulls on CraftResponse optional fields.

Serialize reasonCode and xpGrantSummary as null when absent so Bruno
deny tests match inventory POST wire shape; assert JSON nulls in API tests.

bruno/neon-sprawl-server/craft/Post craft gather refine make spine.bru

@@ -126,7 +126,7 @@ tests {
     const body = res.getBody();
     expect(body.schemaVersion).to.equal(1);
     expect(body.success).to.equal(true);
-    expect(body.reasonCode).to.be.undefined;
+    expect(body.reasonCode).to.equal(null);
     expect(body.outputsGranted).to.deep.include({ itemId: "field_stim_mk0", quantity: 1 });
     expect(body.xpGrantSummary).to.be.an("object");
     expect(body.xpGrantSummary.skillId).to.equal("refine");

bruno/neon-sprawl-server/craft/folder.bru

@@ -3,5 +3,5 @@ meta {
 }
 
 docs {
-  NEO-70 craft HTTP. Run order within folder: deny requests (seq 1–4) then spine (seq 5). Full collection runs after dotnet test on shared Postgres — insufficient-materials clears refined stock; spine reuses persisted scrap and tolerates node_depleted gathers. Deny setup requests may use inventory POST only where noted.
+  NEO-70 craft HTTP. CraftResponse emits explicit null for reasonCode / xpGrantSummary when absent (mirror inventory POST). Run order within folder: deny requests (seq 1–4) then spine (seq 5). Full collection runs after dotnet test on shared Postgres — insufficient-materials clears refined stock; spine reuses persisted scrap and tolerates node_depleted gathers. Deny setup requests may use inventory POST only where noted.
 }

server/NeonSprawl.Server.Tests/Game/Crafting/PlayerCraftApiTests.cs

@@ -104,6 +104,8 @@ public sealed class PlayerCraftApiTests
         Assert.Equal("refine", body.XpGrantSummary!.SkillId);
         Assert.Equal(RefineSkillXpConstants.ActivityXpPerCraftRefineCompletion, body.XpGrantSummary.Amount);
         Assert.Equal(RefineSkillXpConstants.ActivitySourceKind, body.XpGrantSummary.SourceKind);
+        var json = await response.Content.ReadAsStringAsync();
+        Assert.Contains("\"reasonCode\":null", json, StringComparison.Ordinal);
     }
 
     [Fact]
@@ -179,6 +181,9 @@ public sealed class PlayerCraftApiTests
         Assert.Empty(body.InputsConsumed);
         Assert.Empty(body.OutputsGranted);
         Assert.Null(body.XpGrantSummary);
+        var json = await response.Content.ReadAsStringAsync();
+        Assert.Contains("\"reasonCode\":\"unknown_recipe\"", json, StringComparison.Ordinal);
+        Assert.Contains("\"xpGrantSummary\":null", json, StringComparison.Ordinal);
     }
 
     [Fact]

server/NeonSprawl.Server/Game/Crafting/CraftWireDtos.cs

@@ -30,7 +30,6 @@ public sealed class CraftResponse
     public bool Success { get; init; }
 
     [JsonPropertyName("reasonCode")]
-    [JsonIgnore(Condition = JsonIgnoreCondition.WhenWritingNull)]
     public string? ReasonCode { get; init; }
 
     [JsonPropertyName("inputsConsumed")]
@@ -40,7 +39,6 @@ public sealed class CraftResponse
     public required IReadOnlyList<CraftIoAppliedJson> OutputsGranted { get; init; }
 
     [JsonPropertyName("xpGrantSummary")]
-    [JsonIgnore(Condition = JsonIgnoreCondition.WhenWritingNull)]
     public CraftXpGrantSummaryJson? XpGrantSummary { get; init; }
 }