M6.13: Sex picker + species variant schema

Adds character Sex (male/female) as a top-level CharacterDraft field
required for every character, and species variants as a layer on top
of the base species record. Two variant axes:

  - "sex": auto-resolves from CharacterDraft.Sex for purebreds; for
           hybrids, pinned by parent role (sire = male, dam = female)
           by definition. No picker needed beyond Step 0.
  - "lineage": explicit per-species pick (Ram-Folk's sheep/goat). Has
               its own picker on Step 1 (purebred path under the grid;
               hybrid path embedded into the per-parent pick column).

Schema (Theriapolis.Core/Data):
  - SpeciesDef gains VariantAxis (string) and Variants (array of
    SpeciesVariantDef { Id, Name, Traits, Detriments }).
  - JSON content not yet populated — that's M6.14.

CharacterDraft adds:
  - Sex (required by Step 0 validation)
  - SpeciesVariant / SireSpeciesVariant / DamSpeciesVariant
  - ResolveVariantId(species, role) that returns the active variant
    id for a given context — used by Aside to layer variant traits
    onto the base species traits.

Step 0 (StepClade): sex picker row above the hybrid toggle. Two
toggle buttons radio-style.

Step 1 (StepSpecies): purebred path renders a lineage picker below
the grid when the picked species has VariantAxis == "lineage";
hybrid path embeds a lineage picker at the top of each parent's
pick column. Hover popovers summarise each variant's contents.

Validation: Sex is required at Step 0. Lineage variant required at
Step 1 for any picked species (purebred or per-hybrid-parent) with
VariantAxis == "lineage".

Aside: AddVariantContent layers the resolved variant's extra
traits/detriments onto the base species rendering, for both purebred
and hybrid paths.

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

Theriapolis.Godot/Scenes/Aside.cs

@@ -269,10 +269,14 @@ public partial class Aside : MarginContainer
         // (single-pick each, per doc) plus the four universal detriments.
         if (_draft.IsHybrid)
         {
-            AddPickedSpeciesPick(flow, CodexContent.SpeciesById(_draft.SireSpeciesId),
+            var sireSp = CodexContent.SpeciesById(_draft.SireSpeciesId);
+            var damSp  = CodexContent.SpeciesById(_draft.DamSpeciesId);
+            AddPickedSpeciesPick(flow, sireSp,
                 _draft.SireChosenSpeciesTrait, _draft.SireChosenSpeciesDetriment);
-            AddPickedSpeciesPick(flow, CodexContent.SpeciesById(_draft.DamSpeciesId),
+            AddPickedSpeciesPick(flow, damSp,
                 _draft.DamChosenSpeciesTrait, _draft.DamChosenSpeciesDetriment);
+            AddVariantContent(flow, sireSp, _draft.ResolveVariantId(sireSp, "sire"));
+            AddVariantContent(flow, damSp,  _draft.ResolveVariantId(damSp,  "dam"));
 
             // Universal hybrid detriments — every hybrid has all four.
             foreach (var (name, desc) in UniversalHybridDetriments)
@@ -280,7 +284,9 @@ public partial class Aside : MarginContainer
         }
         else
         {
-            AddSpeciesTraits(flow, CodexContent.SpeciesById(_draft.SpeciesId));
+            var sp = CodexContent.SpeciesById(_draft.SpeciesId);
+            AddSpeciesTraits(flow, sp);
+            AddVariantContent(flow, sp, _draft.ResolveVariantId(sp, ""));
         }
 
         // Class level-1 features.
@@ -362,6 +368,22 @@ public partial class Aside : MarginContainer
             flow.AddChild(new TraitChip { TraitName = d.Name, Description = d.Description, Detriment = true });
     }
 
+    /// <summary>Render the resolved variant's extra traits/detriments,
+    /// if any. <paramref name="variantId"/> is the variant key (e.g. "male"
+    /// or "sheep"); empty when no resolution applies.</summary>
+    private static void AddVariantContent(HFlowContainer flow,
+                                           Theriapolis.Core.Data.SpeciesDef? species,
+                                           string variantId)
+    {
+        if (species is null || string.IsNullOrEmpty(variantId)) return;
+        var variant = System.Array.Find(species.Variants, v => v.Id == variantId);
+        if (variant is null) return;
+        foreach (var t in variant.Traits)
+            flow.AddChild(new TraitChip { TraitName = t.Name, Description = t.Description });
+        foreach (var d in variant.Detriments)
+            flow.AddChild(new TraitChip { TraitName = d.Name, Description = d.Description, Detriment = true });
+    }
+
     /// <summary>Hybrid: one chosen species trait + one chosen species detriment.</summary>
     private static void AddPickedSpeciesPick(HFlowContainer flow, Theriapolis.Core.Data.SpeciesDef? species,
                                               string chosenTraitId, string chosenDetrimentId)