0.18.0

SwiftTUI 0.18.0 improves variable-height collection scrolling, fixes composed
layout and terminal behavior, and makes browser renderer packaging explicit.

Added

• App-owned browser bundles for the terminal companion, selected through
  WebHostConfig.browserAssetsPath or the runtime configuration. Build a
  standalone Canvas or experimental DOM companion with swifttui-web build:web
  (STUI-945).
• Text-clipping benchmarks and a text_line_visits work counter. Thanks to
  @vmarcella for
  #52.

Changed

• The bundled terminal companion ships only Canvas and its semantic sidecar.
  Experimental DOM requires an app-owned bundle; ?renderer=dom cannot switch
  the built-in companion. DOM bundles use packaged Ioskeley Mono fonts
  (STUI-926, STUI-945).
• Lists, tables, and lazy stacks share sparse measured row geometry for
  layout, scroll extents, and target refinement (STUI-921).

Fixed

• Retain variable row heights across worker snapshots so upward keyboard
  navigation preserves selection, focus, and visible row geometry. Preserve
  final-row and footer navigation, multi-selection painting, and pending
  scrollTo refinement (STUI-921, STUI-927–STUI-941,
  #56).
• Preserve authored child layout in custom DisclosureGroupStyle content.
  Thanks to @echoz for the contribution in
  #49.
• Respect declared Spacer minima and wrapped flexibility, retain nested
  destination state, preserve scroll viewport ownership through custom Layout
  placement, and reject estimate-derived wrappers for exact measurement reuse.
• Coordinate terminal probes with reader-mode capabilities, detect terminal
  protocols independently, detach link-helper standard descriptors, and honor
  termination requests raised during exit flushing (STUI-927–STUI-941).
• Isolate benchmark render modes and make PTY cleanup regressions independent
  of concurrent descriptor reuse.