fix: writer/reader correctness and determinism issues

- merge: cloneTable keeps relationships; skip-tables applies to new schemas
- diff: detect schema description/owner changes
- prisma: reader no longer turns relation fields into columns, enum
  detection via declared names; writer type mapping is ordered
- typeorm writer: keep explicit SQL types that cannot be inferred
- drizzle: enum columns call the enum constant; reader resolves them
- mysql/mssql/sqlite writers: honour OutputPath, deterministic column
  and constraint order; mssql live execute covers full schema
- template: ToYAML recovers from panics; Merge nil-pointer loop
- regenerate drizzle fixtures

pkg/merge/merge.go

@@ -82,6 +82,15 @@ func (r *MergeResult) merge(target, source *models.Database, opts *MergeOptions)
 		} else {
 			// Schema doesn't exist, add it
 			newSchema := cloneSchema(srcSchema)
+			if len(opts.SkipTableNames) > 0 {
+				kept := newSchema.Tables[:0]
+				for _, t := range newSchema.Tables {
+					if !opts.SkipTableNames[strings.ToLower(t.SQLName())] {
+						kept = append(kept, t)
+					}
+				}
+				newSchema.Tables = kept
+			}
 			target.Schemas = append(target.Schemas, newSchema)
 			r.SchemasAdded++
 		}
@@ -440,6 +449,8 @@ func cloneTable(table *models.Table) *models.Table {
 		Description: table.Description,
 		Schema:      table.Schema,
 		Comment:     table.Comment,
+		Tablespace:  table.Tablespace,
+		GUID:        table.GUID,
 		Sequence:    table.Sequence,
 		UpdatedAt:   table.UpdatedAt,
 		Columns:     make(map[string]*models.Column),
@@ -469,6 +480,14 @@ func cloneTable(table *models.Table) *models.Table {
 		newTable.Indexes[idxName] = cloneIndex(index)
 	}
 
+	// Clone relationships
+	if table.Relationships != nil {
+		newTable.Relationships = make(map[string]*models.Relationship, len(table.Relationships))
+		for relName, rel := range table.Relationships {
+			newTable.Relationships[relName] = cloneRelation(rel)
+		}
+	}
+
 	return newTable
 }