Adds an id-keyed hierarchical `tree: OverTimeRow[]` sidecar to
getCategoryOverTime, built via the generic buildLeafDrivenTree (#263) as
buildOverTimeTree — leaf-driven, income-first, no top-N / no "Other" bucket.
The name-keyed pivot (data/categories/colors/types/categoryIds) is left
BYTE-IDENTICAL, so the Trends chart and the dashboard render unchanged.
computeOverTimeResults now consumes the id-keyed tree LEAVES (never the
`is_parent` subtotals) grouped by each leaf's category_id-resolved type, so
the section subtotals and the Result-before/net lines are exact: two homonym
categories of different types no longer collide, and a non-top-N income or
transfer category is no longer lumped into "Other" as an expense.
CategoryOverTimeTable renders the tree leaves (every category, id-safe)
instead of the top-N pivot; the chart keeps reading the top-N-capped pivot so
its stacked series stay bounded. OverTimeRow mirrors CategoryDelta's snake_case
hierarchy block (parent_id/is_parent/depth/category_type) so it composes with
collapsibleRows / useCollapsibleGroups for the #265 hierarchy work.
Tests: rewrote overTimeResults.test.ts onto the tree (homonym regression +
leaves-only-not-parents); added buildOverTimeTree suite (nesting, income-first,
grand-total invariance, orphan, A->B->A cycle depth guard) and a
getCategoryOverTime tree-wiring test proving the pivot stays top-N+Other while
the tree carries every category. 720 vitest green, build + tsc green.
Resolves#264
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
