topdata: stop hardcoding the skills dataset location

The skills dataset moved into a tree (skills/core, skills/specs, ...).
Resolve it data-driven instead of by name:

- The required-family check no longer pins skill focus families to
  dataset "skills"; the family spec's child_source names the dataset.
- Affinity generation and display names use the skill_focus spec's
  child_source dataset.
- Child slugs derive from the row key's own namespace (text after the
  first colon) instead of assuming namespace == dataset path.
- The wiki loader accepts both layouts ("skills", then "skills/core").

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

internal/topdata/native.go

@@ -2317,6 +2317,18 @@ func (c *featGeneratedContext) familyHasExistingRows(familyKey string) bool {
 	return false
 }
 
+// skillsDatasetName returns the dataset the skill_focus family sources its
+// children from. The skills dataset location is data-driven via that spec;
+// "skills" is only the fallback when no spec is loaded.
+func (c *featGeneratedContext) skillsDatasetName() string {
+	for key, spec := range c.familySpecs {
+		if normalizeKeyIdentity(key) == "skillfocus" && spec.ChildSource.Dataset != "" {
+			return spec.ChildSource.Dataset
+		}
+	}
+	return "skills"
+}
+
 func (c *featGeneratedContext) datasetRows(name string) (map[string]map[string]any, error) {
 	if rows, ok := c.rowsByDataset[name]; ok {
 		return rows, nil
@@ -2555,7 +2567,10 @@ func buildFamilyExpansionGeneratedModule(path string, obj map[string]any, ctx *f
 		if !include {
 			continue
 		}
-		slug := strings.TrimPrefix(sourceKey, spec.ChildSource.Dataset+":")
+		slug := sourceKey
+		if idx := strings.Index(slug, ":"); idx >= 0 {
+			slug = slug[idx+1:]
+		}
 		featKey, rowID, hasID, err := ctx.resolveGeneratedFeatIdentity(spec, slug, row)
 		if err != nil {
 			return nil, fmt.Errorf("generated feat file %s: %w", path, err)
@@ -2655,7 +2670,7 @@ func buildRacialtypesSkillAffinityModule(ctx *featGeneratedContext) (map[string]
 	if len(grants) == 0 {
 		return nil, nil
 	}
-	skillRows, err := ctx.datasetRows("skills")
+	skillRows, err := ctx.datasetRows(ctx.skillsDatasetName())
 	if err != nil {
 		return nil, err
 	}
@@ -2854,7 +2869,7 @@ func (c *featGeneratedContext) displayNameForGeneratedSource(dataset string, row
 		return text
 	}
 	switch dataset {
-	case "skills":
+	case c.skillsDatasetName():
 		return displayNameForSkill(row)
 	case "baseitems":
 		return displayNameForBaseitem(row)