DBmaps 0.1.0

• Initial release of DBmaps.
• Added table_info() to define table metadata and aggregations.
• Added map_join_paths() to discover join paths from metadata and, optionally, from data (inferred joins).
• Added create_join_plan() to translate a user’s request into a step-by-step, executable plan.
• Added execute_join_plan() to run the generated plan and produce a final data.table.
• Added plot_join_plan() to visualize the execution plan as a flowchart.
• Added four sample datasets (customers, products, transactions, views) for examples and testing.
• Added a main vignette (DBmaps-introduction) demonstrating the full package workflow.
• Submitted to CRAN.