Implements the epic's uncovered P0 economy backlog item (flip candidates).
Verified source chain 2026-08-27: prices.runescape.wiki mapping + latest,
all 15 shortlist limits cross-checked against Module:Exchange (agree);
GE tax verified at 2% since 2025-05-29 (1% at 2021 intro), 5M/item cap,
sub-50gp effectively untaxed; Merchanting + Grand Exchange/Buying limits
pages cited for mechanics. Net model: 0.98*sell - buy at band edges.
Gate: python3 tools/validate.py exit 0 (2 entries, 0 errors, 1 pre-existing
warning on the golden entry's researched flag — none added by this entry).
04a4af0299