Yahoo's dividend endpoint returns the fund's TOTAL per-share distribution
(dividend + capital gain) for many share classes while the capitalGains
endpoint returns the cap-gain portion separately; summing both double-counted
cap gains and broke pre/post-tax comparability (after-tax engine could beat
the adj-based pre-tax return: impossible).
Add _fix_total_distributions to the bundle-assembly invariants
(layout-agnostic, survives re-downloads): on same-date div>capg events, the
exact Yahoo-adj implied distribution (d = P - Q*A_{t-1}/A_t) must match the
div-file amount (not the sum) on >=3 dates before rewriting div -= capg.
Self-validating: genuine separate same-date distributions are untouched.
Rewrote 17,900 cells on 1,957 symbols.
Pool check (scripts/check_adj_consistency.py): all 14 symbols now
TR(close+events) == TR(adj) to 0.01pt and post < pre with plausible drags.
Tests: rewrite case, no-rewrite case, idempotency (tests/test_data.py).
