Replace the SCF net worth target with Fed Financial Accounts net worth

[MaxGhenis]

The current net_worth calibration target is sourced from the Survey of Consumer Finances (SCF). SCF is valuable for micro distribution work, but for the national aggregate a better benchmark is the Federal Reserve's Financial Accounts (Z.1).

Why the current target is weak:

• SCF is a survey benchmark, not the Fed's main aggregate balance-sheet account.
• For a national macro total, the official Z.1 Financial Accounts series is more authoritative and updated more regularly.
• Distributional Financial Accounts (DFA) can still be used as a distributional cross-check if needed.

Proposed change:

• Replace the SCF-based aggregate net_worth target with the Federal Reserve Z.1 Financial Accounts household-and-nonprofit net worth aggregate, documenting the sector scope.
• Use SCF/DFA only for diagnostics or future distributional calibration, not the main national hard target.

Primary sources:

• Fed Z.1 / Financial Accounts: https://www.federalreserve.gov/releases/z1/
• Fed DFA overview: https://www.federalreserve.gov/releases/z1/dataviz/dfa/
• Fed SCF overview: https://www.federalreserve.gov/econres/aboutscf.htm