gui_toolkit 0.44.0

Added

• platform.frame_decision: the cadence model (platform/pacing.odin, docs/pacing.md): a plan from the screen and the application's choices (cadence_plan: the top useful rate of a variable refresh screen, Frame_Slots strict or loose), a state per frame (Rest, Continuous, Drag, Input_Answer, Resize_Step, Resize_Burst) and one pure decision (Frame_Decision: the wait for its slot, whether it waits for the swap chain, whether it is presented at once, the swap chain's latency), plus cadence_inner_frame, cadence_echo and the frame clock (frame_clock_advance, vblank_at_or_before). Test: tests/pacing (states, transitions, and simulated runs on fixed and variable refresh screens, tearing, a 1 kHz mouse, a resize, a panel dragged, AltSnap); tests/frame_slots and tests/pacing join the windowless tests of the CI.