fix(dbml): resolve commented cross-file // Ref: lines

Commented refs are collected per file and resolved against the combined
model after all inputs are loaded (directory, --from-list, merge, jobs).
Matched refs become FKs and relationships; duplicates of existing FKs are
skipped; missing targets are skipped with a warning; column type
mismatches warn.

Also keep reused index names within a DBML table instead of overwriting,
give a second FK to the same table a distinct relationship name, and make
the pgsql writer match relationships to FKs by name first.

pkg/writers/pgsql/writer_test.go

@@ -1549,3 +1549,52 @@ func TestGenerateColumnDefinition_IdentityColumnEmitsIdentityClauseNotDefault(t
 		t.Fatalf("generateColumnDefinition() = %q, want %q", got, want)
 	}
 }
+
+// Two FKs to the same table: each relationship must emit its own FK columns,
+// not whichever FK map iteration returns first.
+func TestWriteDatabase_MultipleForeignKeysToSameTable(t *testing.T) {
+	db := models.InitDatabase("testdb")
+	schema := models.InitSchema("public")
+
+	dept := models.InitTable("department", "public")
+	id := models.InitColumn("id_department", "department", "public")
+	id.Type = "bigint"
+	id.IsPrimaryKey = true
+	dept.Columns["id_department"] = id
+
+	emp := models.InitTable("employee", "public")
+	for _, name := range []string{"rid_department", "rid_manager"} {
+		col := models.InitColumn(name, "employee", "public")
+		col.Type = "bigint"
+		emp.Columns[name] = col
+
+		fkName := "fk_employee_" + name
+		fk := models.InitConstraint(fkName, models.ForeignKeyConstraint)
+		fk.Schema, fk.Table, fk.Columns = "public", "employee", []string{name}
+		fk.ReferencedSchema, fk.ReferencedTable, fk.ReferencedColumns = "public", "department", []string{"id_department"}
+		emp.Constraints[fkName] = fk
+
+		rel := models.InitRelationship("employee_to_department_"+name, models.OneToMany)
+		rel.FromTable, rel.ToTable, rel.ToSchema, rel.ForeignKey = "employee", "department", "public", fkName
+		emp.Relationships[rel.Name] = rel
+	}
+
+	schema.Tables = append(schema.Tables, dept, emp)
+	db.Schemas = append(db.Schemas, schema)
+
+	for i := 0; i < 20; i++ {
+		var buf bytes.Buffer
+		writer := NewWriter(&writers.WriterOptions{})
+		writer.writer = &buf
+		if err := writer.WriteDatabase(db); err != nil {
+			t.Fatalf("WriteDatabase failed: %v", err)
+		}
+		output := buf.String()
+		for _, name := range []string{"rid_department", "rid_manager"} {
+			want := "ADD CONSTRAINT fk_employee_" + name + "\n      FOREIGN KEY (" + name + ")"
+			if !strings.Contains(output, want) {
+				t.Fatalf("run %d: missing %q in output:\n%s", i, want, output)
+			}
+		}
+	}
+}