v0.5.2

Add sparse matrix support — sparse now introduces a sparse runtime value with display, metadata, class, whos, indexing, element-wise arithmetic, reductions, transposes, find, nnz, JSON/string conversion, WASM wire previews, and GPU fallback/residency integration. Add optimization and linear-algebra builtins — linprog and rref now execute through runtime, VM, docs metadata, and generated builtin registration paths. Add table and import workflows — readtable, table objects, table Properties, dot/paren/brace table access and assignment, variable renaming, height, width, groupsummary, table-aware sortrows, datetime import support, and spreadsheet/text import plumbing cover common MATLAB tabular scripts. Add image and signal builtins — imhist and butter now cover histogram and Butterworth-filter workflows with runtime, VM, docs metadata, and WebAssembly registry integration. Add SISO transfer-function control workflows — tf('s'), tf('z', Ts), transfer-function algebra, feedback, dcgain, pole, isstable, stepinfo, and multi-system step plotting/output forms now cover common control scripts