feat(query-api): add richer stats and retention

internal/store/postgres/postgres.go

@@ -3,6 +3,8 @@ package postgres
 import (
 	"context"
 	"database/sql"
+	"time"
+
 	_ "github.com/jackc/pgx/v5/stdlib"
 )
 
@@ -15,6 +17,9 @@ func Open(url string) (*DB, error) {
 	if err != nil {
 		return nil, err
 	}
+	db.SetMaxOpenConns(25)
+	db.SetMaxIdleConns(5)
+	db.SetConnMaxLifetime(5 * time.Minute)
 	return &DB{sql: db}, nil
 }