Write the shared helper toolkit (first 3 functions)

Write profile_table(df), missing_report(df) and save_fig(fig, name) in eda_utils.py and import them in both notebooks. Concepts: Python functions reused from Fundamentals B05; DRY principle Project A: Call profile_table(df_credit): dtype, n_unique, nulls, role (numeric / categorical / ID / target), sample value — your notebook's Cell 7 profile becomes this reusable helper. Project B: Call profile_table(df_energy).