SwiftTUI 0.16.0

More content and controls participate in accessibility, interactive terminal
sessions gain a shared browser companion, and terminal input, PTY output and
shutdown paths have bounded ownership. This release also fixes layout,
animation, drawing and navigation regressions accumulated since 0.15.1.

Added

• Ordinary static text and explicit Text.paragraph() semantics, semantic
  grouping and unpainted accessibility representations, custom assistive
  actions, independent accessibility focus bindings, and named navigation
  regions (STUI-579, STUI-652, STUI-655, STUI-656).
• Shared widget properties and relationships; stable Picker choices and
  option geometry; progress and spinner meaning; collection structure,
  selection and outline disclosure; and composite navigation and presentation
  semantics. Offscreen collection content can be revealed for review without
  selecting it (STUI-654, STUI-657 to STUI-661).
• Directed browser text edits and selection ranges, with structured source
  prose and secure-text boundaries (STUI-662).
• A shared browser companion for retained interactive terminal scenes on
  macOS, Linux and Windows. Interactive launches start it by default;
  SWIFTTUI_COMPANION=off opts out. Scene selection and pointer input follow
  the presented viewport (STUI-665, STUI-666, STUI-667).
• Live accessibility preferences across hosts and styles, including reduced
  motion, reduced transparency, composited contrast and color adaptation
  (STUI-668 to STUI-671).

Changed

• Require swift-collections 1.7.2 or later within 1.x. This lifts the
  temporary 1.7.0 cap after upstream fixed the Swift 6.4 borrow-runtime
  references that prevented deployment to macOS/iOS versions before 27
  (STUI-907; apple/swift-collections#733).
• Publish measured collection offsets for wheel chaining and share immutable
  resolve continuation scopes and live registration paths to reduce repeated
  work (STUI-650, STUI-711).
• Missing-label diagnostics describe both simple accessibility labels and
  richer accessibility representations. Accessibility extraction, composed
  actions and review-cursor bounds handle large or unusual inputs without
  broadening their claims beyond the documented host support.

Fixed

• Bound WebHost ingress and receive-task lifetimes, make PTY writes
  cancellable, close owned descriptors, retain lossless PTY output under
  backpressure, and bound terminal teardown before restoring terminal modes.
  Blocked input is released before draining the PTY exit tail (STUI-645,
  STUI-884, STUI-894 to STUI-898).
• Recover terminal input across chunks without recursive parsing, clamp
  animated-image timing without overflow, and reap spawned link helpers
  without blocking the caller (STUI-826, STUI-891 to STUI-893, STUI-899).
• Scroll momentum keeps one deadline chain instead of scheduling redundant
  follow-up deadlines. Empty NO_COLOR values no longer disable color, and
  unpresented diagnostic frames no longer count as full repaints
  (STUI-900, STUI-901, STUI-902).
• Default progress text matches its clamped numeric value; menu Pickers close
  after a changed pointer selection; different navigation presentation
  bindings cannot reuse each other's destination state; and leading path
  lines retain their implicit origin (STUI-903 to STUI-906).
• Correct oversized alignment, rigid fixedSize spacers, foreign-surface
  sizing and damage, retained tall collection rows, final-row scrolling, and
  wheel chaining through non-overflowing or single-axis views (STUI-590,
  STUI-591, STUI-594, STUI-598, STUI-611, STUI-613, STUI-616, STUI-626).
• Correct zero-opacity drawing, open-path containment, stroke-trim animation,
  matched-geometry destinations, keyframe retrigger values and inherited
  velocities, and one-shot reduced-motion end values (STUI-592, STUI-603,
  STUI-605, STUI-609, STUI-610, STUI-612, STUI-627).
• Preserve composite gesture values and keyboard traversal across pointer
  cancellation; keep hosted sessions alive after exit keys; and terminate
  Android run loops when their host stops its readers (STUI-582, STUI-587,
  STUI-588, STUI-614, STUI-709, STUI-712).

Integration notes

• Host integrations switching exhaustively over AccessibilityAction or
  AccessibilityActionKind must handle the new custom-action, text-edit,
  text-selection, accessibility-focus and accessibility-blur cases.
• Pair framework and browser 0.16.0 for the new semantic and preference
  transport. Automated transport and geometry coverage does not expand the
  recorded assistive-technology acceptance beyond the documented journeys.