- Add K1BoxDefinition, K1LineItem, K1AggregationRule, PartnershipMembership, PartnershipValuation models
- Replace CellMapping with K1BoxDefinition module (IRS box definitions + 15 aggregation rules)
- Add K1MaterializedView service for partnership schedule rollups
- Expand aggregation rules from 3 to 15 on frontend verification page
- Fix box key 4c -> 4b in Guaranteed Payments and Total K-1 Income rules
- Add box 19 to Total Distributions rule sourceBoxKeys
- Add Cell Mapping page with aggregation rules table and IRS box definitions
- Fix Cell Mapping page routing (was falling through to wildcard)
- Add Material Icons font to index.html
- Fix text cut-off in K-Document form section titles
- Fix table column widths on K1 Import History page
- Add BOX_KEY_TO_K1DATA_FIELD mapping for confirm pipeline
- Add distribution creation fallback (box 19 total / L_WITHDRAWALS)
- Auto-populate membership capital and partnership valuation on confirm
- Improve 'no active members' error message with tax year context
- Add Prisma migrations for normalized model, drop cell-mapping, widen precision, materialized views
- Add spec 006 documentation and test fixtures