feat(merge): enhance type conflict detection for columns

* Introduced extractTypeParts function to handle embedded dimensions in type strings.
* Updated columnTypeConflict to utilize new type extraction logic.
* Improved PostgreSQL type normalization and handling in various components.

pkg/merge/merge.go

@@ -5,9 +5,11 @@ package merge
 
 import (
 	"fmt"
+	"strconv"
 	"strings"
 
 	"git.warky.dev/wdevs/relspecgo/pkg/models"
+	"git.warky.dev/wdevs/relspecgo/pkg/pgsql"
 )
 
 // MergeResult represents the result of a merge operation
@@ -449,10 +451,40 @@ func columnTypeConflict(target, source *models.Column) bool {
 		return false
 	}
 
-	return normalizeType(target.Type) != normalizeType(source.Type) ||
-		target.Length != source.Length ||
-		target.Precision != source.Precision ||
-		target.Scale != source.Scale
+	tType, tLen, tPrec, tScale := extractTypeParts(target)
+	sType, sLen, sPrec, sScale := extractTypeParts(source)
+
+	return tType != sType || tLen != sLen || tPrec != sPrec || tScale != sScale
+}
+
+// extractTypeParts returns the canonical base type and dimensions for a column,
+// handling the case where dimensions are embedded in the type string (e.g. "char(2)")
+// rather than stored in the separate Length/Precision/Scale fields.
+func extractTypeParts(col *models.Column) (baseType string, length, precision, scale int) {
+	typeName := strings.ToLower(strings.TrimSpace(col.Type))
+	length, precision, scale = col.Length, col.Precision, col.Scale
+
+	if idx := strings.Index(typeName, "("); idx >= 0 {
+		inner := strings.TrimRight(strings.TrimSpace(typeName[idx+1:]), ")")
+		typeName = strings.TrimSpace(typeName[:idx])
+		parts := strings.Split(inner, ",")
+		if len(parts) == 2 {
+			if p, err := strconv.Atoi(strings.TrimSpace(parts[0])); err == nil && p > 0 && precision == 0 {
+				precision = p
+			}
+			if s, err := strconv.Atoi(strings.TrimSpace(parts[1])); err == nil && s > 0 && scale == 0 {
+				scale = s
+			}
+		} else if len(parts) == 1 {
+			if l, err := strconv.Atoi(strings.TrimSpace(parts[0])); err == nil && l > 0 && length == 0 && precision == 0 {
+				length = l
+			}
+		}
+	}
+
+	typeName = pgsql.NormalizePGType(typeName)
+
+	return typeName, length, precision, scale
 }
 
 func normalizeType(value string) string {