New src/lib/algorithms/redBlack.js: a Red-Black planner with full insert,
delete (transplant + two-child successor copy + the four double-black fix-up
cases), and search. It runs the standard CLRS algorithm on a mutable working
copy (parent pointers + nil sentinel, ids preserved) and emits a setTree
snapshot after each rotation / recolor, so every fix-up step animates.

The /bst page gains a tree-type dropdown (BST / Red-Black); switching reseeds
the tree. tree-node renders red/black fill with the operation highlight as an
outer ring and a fill transition for smooth recoloring; tree-canvas passes the
node color; useTreeEditor gains reset(); TreeMenu gains an optional mode
dropdown. Home card renamed to "Binary Search Trees".

The recursion-tree builders + recursionActions planner now live in
src/lib/algorithms/recursion.js (was app/recursion-tree/fib.jsx), alongside the
other action-log planners. Also deletes the unused legacy app/recursion-tree/bst.js.

New /binary-heap segment on the reusable tree component: a min-heap with
insert (sift-up), extract-min (sift-down), build-heap from a typed list
(Floyd O(n) heapify), and heapsort (descending, since it's a min-heap).

src/lib/algorithms/heap.js keeps the heap as an array of {id,value} and
rebuilds a complete binary tree per setTree; sifts swap entries with their ids
so nodes slide past each other on the rAF tween. Reuses binaryLayout and the
existing node states (amber = active pair, green = sorted). Adds a heap-specific
menu and a home card (placeholder image).