M6.5: StepSkills + ability-bonus breakdown + Aside redesign

The skills step lands as the last data-driven character creation step
(only Sign — name + confirm — remains for M6.6). Brought a few cross-
cutting refactors with it.

Scenes/Steps/StepSkills.cs:
  Direct port of StepSkills in src/steps.jsx — all 18 skills laid out
  in 6 ability-grouped panels (STR/DEX/CON/INT/WIS/CHA), 2-column
  grid. Background-granted skills appear pre-checked and locked;
  user picks `class.SkillsChoose` more from `class.SkillOptions`.
  Hover the skill name → popover with the codex flavor description
  (limited to the title only — hovering checkboxes / source tags
  doesn't trigger the popover, avoids interference with adjacent
  rows' click targets). Fixed-width [✓] / [ ] / [—] checkbox slot
  so toggling doesn't shift the row layout.

UI/SkillsCatalog.cs (new):
  Static skill table — JSON id, display label, governing ability,
  and the codex SKILL_DESC text ported verbatim from src/data.jsx.
  Mirrors Theriapolis.Core.Rules.Stats.SkillId; descriptions live
  here because backgrounds.json and classes.json don't carry them.

UI/AbilityCalc.cs (new):
  Final-score math — base assignment + clade and species mods, with
  per-source breakdown for the bonus popover ("+1 from Canidae · +2
  from Wolf"). Hybrid mode tags each clade source with its lineage
  ("(sire)" / "(dam)"). Used by both StepStats and the Aside so the
  two views can never disagree on what a +N badge means.

UI/BackgroundAvailability.cs (new):
  Extracted from StepBackground — shared rules table for hybrid-only
  and clade-restricted backgrounds. Now also consulted by StepClade
  when the player changes lineage: the currently-selected background
  is auto-cleared if the new lineage no longer satisfies its rule
  (e.g., Pack-Raised clears when switching from Canidae to Felidae,
  Passer clears when toggling Hybrid off). Implemented via
  Resource.Duplicate + Patch on the duplicate to evaluate the
  hypothetical post-patch state without committing prematurely.

StepStats.cs:
  Per-row layout extended: ability label | slot | bonus chip | final
  | d20 mod. Bonus chip is a TraitChip with the per-source breakdown
  in its hover description. Auto-assign now sorts empty abilities by
  AbilityCalc.TotalBonus DESCENDING (with class.PrimaryAbility as
  tiebreaker) — biggest pool value lands on the ability already
  receiving the biggest lineage bonus, maximising final scores.

Aside.cs (significant redesign):
  - Name centered at top.
  - Lineage details: 2-column grid, full-width.
    - Purebred:  Clade | Species, then Calling | Background, then
                 Subclass | (empty).
    - Hybrid:    SIRE ★ | DAM (centered + underlined column heads),
                 Clade | Clade, Species | Species, then the same
                 calling/background/subclass rows.
  - Attributes: STR/DEX/CON/INT/WIS/CHA each with bonus chip (omitted
    when +0), final score, d20 modifier. Self-contained min-width
    table so it can't widen the panel beyond its alloc.
  - Pills: traits, detriments, level-1 features, background feature,
    skill chips (BG-locked + user-chosen). All hoverable for descriptions.
  - Whole panel wraps in a ScrollContainer so an over-tall summary
    scrolls in place instead of pushing the wizard layout off-screen.
  - Width nudged 320 → 360px. Smaller font on label tags, autowrap
    on value labels so long names ("Hybrid Underground") wrap rather
    than push the panel wider.

Card grids: changed all five card-grid steps (Clade, Species, Class,
Subclass, Background) from SizeFlagsHorizontal.ExpandFill →
ShrinkCenter. Cards stay at their CustomMinimumSize 200 wide and
the grid horizontally centers in PageMain. The right-side gap
between content and Aside is now uniform regardless of how many
cards or whether the last row is partial — fixes the "Clade tab
feels too padded, Background tab too tight" perception.

Closes M6.5. Per guide §12, what's left in M6: M6.6 (StepReview —
name + summary + Confirm handoff per guide §11) and M6.7 (parchment
Theme pass).

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

Theriapolis.Godot/Scenes/Steps/StepStats.cs

@@ -33,6 +33,9 @@ public partial class StepStats : VBoxContainer, IStep
     private CharacterDraft _draft = null!;
     private AbilityPool _pool = null!;
     private readonly Dictionary<string, AbilitySlot> _slots = new();
+    private readonly Dictionary<string, TraitChip> _bonusChips = new();
+    private readonly Dictionary<string, Label> _finalLabels = new();
+    private readonly Dictionary<string, Label> _dModLabels = new();
     private Button _arrayBtn = null!;
     private Button _rollBtn = null!;
     private Button _rerollBtn = null!;
@@ -125,6 +128,34 @@ public partial class StepStats : VBoxContainer, IStep
                 => HandleSlotDrop(payload, captured);
             _slots[captured] = slot;
             row.AddChild(slot);
+
+            // Bonus chip — hover for the per-source breakdown.
+            var bonus = new TraitChip { TraitName = "+0", Description = "" };
+            bonus.CustomMinimumSize = new Vector2(56, 0);
+            _bonusChips[captured] = bonus;
+            row.AddChild(bonus);
+
+            // Final score (= base + total bonus).
+            var finalLbl = new Label
+            {
+                Text = "—",
+                CustomMinimumSize = new Vector2(48, 0),
+                HorizontalAlignment = HorizontalAlignment.Right,
+                VerticalAlignment = VerticalAlignment.Center,
+            };
+            _finalLabels[captured] = finalLbl;
+            row.AddChild(finalLbl);
+
+            // d20 modifier from final score.
+            var dModLbl = new Label
+            {
+                Text = "",
+                CustomMinimumSize = new Vector2(48, 0),
+                HorizontalAlignment = HorizontalAlignment.Right,
+                VerticalAlignment = VerticalAlignment.Center,
+            };
+            _dModLabels[captured] = dModLbl;
+            row.AddChild(dModLbl);
         }
 
         Refresh();
@@ -161,6 +192,23 @@ public partial class StepStats : VBoxContainer, IStep
             _pool.AddChild(token);
         }
 
+        // Bonus / final / d20 mod per ability — updated in place from the
+        // computed mod sources so the row stays stable across drops.
+        foreach (var ab in Abilities)
+        {
+            int bonus = AbilityCalc.TotalBonus(ab, _draft);
+            int baseScore = AbilityCalc.BaseScore(ab, _draft);
+            int final = baseScore + bonus;
+            int dMod = AbilityCalc.D20Modifier(final);
+
+            _bonusChips[ab].SetTrait(
+                AbilityCalc.FormatSigned(bonus),
+                AbilityCalc.FormatBreakdown(AbilityCalc.Sources(ab, _draft)),
+                tag: "bonus");
+            _finalLabels[ab].Text = baseScore == 0 ? "—" : final.ToString();
+            _dModLabels[ab].Text = baseScore == 0 ? "" : AbilityCalc.FormatSigned(dMod);
+        }
+
         // Slots: token if assigned, otherwise dash placeholder.
         foreach (var (ab, slot) in _slots)
         {
@@ -265,12 +313,16 @@ public partial class StepStats : VBoxContainer, IStep
     {
         if (_draft.StatPool.Count == 0) return;
 
-        // Empty slots, ordered by class primary abilities first.
+        // Empty slots, ordered DESCENDING by their clade+species bonus —
+        // highest pool value goes to the ability with the highest bonus
+        // already coming in, maximising the final score on each. Ties
+        // broken by class.PrimaryAbility order.
         var cls = CodexContent.Class(_draft.ClassId);
         var primary = cls?.PrimaryAbility ?? System.Array.Empty<string>();
         var emptyAbilities = Abilities
             .Where(a => !_draft.StatAssign.ContainsKey(a))
-            .OrderBy(a =>
+            .OrderByDescending(a => AbilityCalc.TotalBonus(a, _draft))
+            .ThenBy(a =>
             {
                 int idx = System.Array.IndexOf(primary, a);
                 return idx < 0 ? 99 : idx;