Time is evaluation, not a widget
================================

Workbench separates four ideas that small tools often combine:

::

   TimeValue (coordinate + units/second)
       != TimeRange (descriptive domain)
       != TimeTransport (playback policy)
       != TimelineWidget (user interaction)

``TimeValue`` uses a floating-point coordinate and rate, allowing subframes and
external time codes. Conversion through seconds preserves meaning across rates.
``TimeRange`` has start and duration and does not clamp evaluation.

``TimeContext`` owns only the current sample, delta, and monotonically increasing
evaluation index. The index distinguishes repeated evaluations at the same time.
It has no playing state, loop mode, or range. ``TimeTransport`` owns those policies:
deterministic seek/step and elapsed-seconds realtime advance both evaluate the same
context. ``TimelineWidget`` adapts buttons and a scrubber to the transport; it does
not own either model.

::

   TimeTransport -> TimeContext -> active consumers
                                      |
                                      `-> host-managed miskeyed.time uniforms

Time changes upload reflected uniform values without changing shader identity or
triggering compilation. This boundary lets a future USD time-code source, OTIO
transport, offline renderer, simulation, or host DCC replace playback policy while
consumers keep the same evaluation input.

Implementation
--------------

Relevant source is ``cpp/include/miskeyed/workbench/core/TimeContext.h``,
``TimeTransport.h``, and ``cpp/src/workbench/ui/TimelineWidget.cpp``.