Topdata Migration (#2)

Native topdata migration summary

- Replaced the legacy 2dabuilder runtime path with the native topdata builder.
- Native build, validate, compare, and convert flows now cover the canonical topdata pipeline.
- compare-topdata is now a native self-check; legacy reference-builder runtime usage was removed.
- Parts generation follows the native asset-scan contract and uses sow-assets via project asset resolution.
- Generated feat families, class-feat injects, masterfeat/successor expansion, and dataset-derived feat generation were brought to parity and regression-covered.
- Remaining mirrored datasets were migrated into native-owned canonical data while preserving lock IDs.
- normalize-topdata bridge behavior and migration-era ownership markers were removed.
- Documentation was rewritten around the native workflow and active contracts were cleaned up.
- Final hardening pass removed stale validator assumptions and cleaned ignored/generated artifacts for PR readiness.

Reviewed-on: https://gitea.westgate.pw/ShadowsOverWestgate/sow-tools/pulls/2
Co-authored-by: vickydotbat <vickydotbat@tutamail.com>
Co-committed-by: vickydotbat <vickydotbat@tutamail.com>

internal/topdata/feat_migrate.go

@@ -0,0 +1,64 @@
+package topdata
+
+import (
+	"encoding/json"
+	"os"
+	"path/filepath"
+)
+
+func importLegacyFeat(referenceBuilderDir, dataDir string, legacyTLK *legacyTLKData) (int, error) {
+	_ = legacyTLK
+
+	legacyDir := filepath.Join(referenceBuilderDir, "data", "feat")
+	if _, err := os.Stat(legacyDir); err != nil {
+		if os.IsNotExist(err) {
+			return 0, nil
+		}
+		return 0, err
+	}
+	legacyBasePath := filepath.Join(legacyDir, "base.json")
+	if _, err := os.Stat(legacyBasePath); err != nil {
+		if os.IsNotExist(err) {
+			return 0, nil
+		}
+		return 0, err
+	}
+
+	targetDir := filepath.Join(dataDir, "feat")
+	targetBasePath := filepath.Join(targetDir, "base.json")
+	var targetObj map[string]any
+	if _, err := os.Stat(targetBasePath); err == nil {
+		targetObj, err = loadJSONObject(targetBasePath)
+		if err != nil {
+			return 0, err
+		}
+	} else if !os.IsNotExist(err) {
+		return 0, err
+	}
+	if targetObj != nil {
+		if rows, ok := targetObj["rows"].([]any); ok && len(rows) > 0 {
+			return 0, nil
+		}
+	}
+
+	baseObj, err := loadJSONObject(legacyBasePath)
+	if err != nil {
+		return 0, err
+	}
+	baseObj["output"] = "feat.2da"
+	baseObj["compare_reference"] = false
+	canonicalizeWikiMetadataDocument(baseObj)
+
+	if err := os.MkdirAll(targetDir, 0o755); err != nil {
+		return 0, err
+	}
+	raw, err := json.MarshalIndent(baseObj, "", "  ")
+	if err != nil {
+		return 0, err
+	}
+	raw = append(raw, '\n')
+	if err := os.WriteFile(targetBasePath, raw, 0o644); err != nil {
+		return 0, err
+	}
+	return 1, nil
+}