Replace direct *pgxpool.Pool usage with PoolProxy wrapper across the entire backend: - db.DB renamed to db.Conn (*pgxpool.Pool -> *PoolProxy) - JWT functions now accept context.Context instead of using context.Background() - Handler DB calls route through PoolProxy for per-test transaction support - Fixture/helper/testdb functions accept Querier interface for decoupling - Query ordering fixed in bookings handlers: COUNT after data query to avoid pgx conn busy - Time truncation fixed: time.Date instead of Truncate(24*time.Hour) for week start calc - testmain_test.go files updated with SeedBaseline and NewPoolProxy Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent) Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>