v0.5.3

One change since v0.5.2.

• A finished thought holds where it ended. v0.5.2 fixed the height of the block under ✻ Thinking… while a thought streams; the close still took its two rows away, so everything above the block dropped by two when the thinking was over. Now the heading becomes ✻ Thought for 2s and the two rows under it stay exactly as the last delta left them — no cut mark, no new row, nothing above moves. A click still goes round: the whole thought in place, then the row alone, then back to the two rows. Plan M78.