feat(03-03): add typed path params and per-plugin rollback

Compile regex and enum constraints at route registration so malformed and unknown IDs share a 404, and named rollback errors isolate one plugin's history.

Co-authored-by: Cursor <cursoragent@cursor.com>

lagoon/migrations_test.go

@@ -2,12 +2,16 @@ package lagoon
 
 import (
 	"bytes"
+	"errors"
 	"io"
 	"os"
 	"strings"
 	"testing"
 
+	"git.golem15.com/golem15/summercms/backpack"
 	"git.golem15.com/golem15/summercms/bonfire"
+	"git.golem15.com/golem15/summercms/party"
+	"gorm.io/gorm"
 )
 
 func TestHistoryTableName(t *testing.T) {
@@ -95,3 +99,27 @@ func TestOpenRequiresDSN(t *testing.T) {
 		t.Fatalf("got %v", err)
 	}
 }
+
+type stubPlugin struct{ id string }
+
+func (s stubPlugin) ID() string                   { return s.id }
+func (s stubPlugin) Requires() []string           { return nil }
+func (s stubPlugin) Register(*backpack.App) error { return nil }
+func (s stubPlugin) Boot(*backpack.App) error     { return nil }
+
+func TestRollbackUnknownPluginIsNamedError(t *testing.T) {
+	err := RollbackLast(&gorm.DB{}, []party.Plugin{stubPlugin{id: "golem15.user"}}, "golem15.missing")
+	if !errors.Is(err, ErrUnknownPlugin) {
+		t.Fatalf("got %v", err)
+	}
+	if !strings.Contains(err.Error(), "golem15.missing") {
+		t.Fatalf("error should name plugin: %v", err)
+	}
+}
+
+func TestRollbackMissingPluginIsNamedError(t *testing.T) {
+	err := RollbackLast(&gorm.DB{}, nil, "")
+	if !errors.Is(err, ErrNoMigrations) {
+		t.Fatalf("got %v", err)
+	}
+}