feat(03-01): add shared postgres pool and plugin migrations

Open one pgx stdlib *sql.DB, hand it to GORM, and run per-plugin
gormigrate sets with isolated history tables after an ICU pl-PL check.

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

bonfire/command.go

@@ -82,7 +82,7 @@ func (in cobraInput) Flag(name string) (string, bool) {
 
 func validCommandName(name string) bool {
 	switch name {
-	case "build", "dev":
+	case "build", "dev", "serve", "migrate":
 		return true
 	}
 	ns, verb, ok := strings.Cut(name, ":")