Kudzu 0.16.22 - Reactive Collection Count Reuse

Removes the first compiler blocker selected by the corrected 0.21.4 AI delivery evidence. Supported filtered collection aliases can now drive keyed rendering, top-level counts, reactive text, and count-selected conditional branches without duplicated state or imperative DOM code. Chrome verifies count updates, empty-branch unmount, and keyed remount. Adds no semantic primitive, compiler pass, runtime concept, public API, dependency, or shared-runtime byte. The 1.0 gate remains blocked.