Tooltips after one second, and at once for the next button

From the development repository at b7ffe0e.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

docs/implementation.md

@@ -278,8 +278,9 @@ file that uses them, so that they can be changed in one place, or offered
 as preferences later: the line widths and the five colours (`main.js`),
 the zoom step of the wheel and the zoom per 100 pixels of a pen drag
 (`renderer.js`), the dead zone of that drag (`pen_input.js`), the margin
-by which the page grows (`page_model.js`), the tooltip delay
-(`tooltip.js`), the hold that moves an image (600 ms, with 6 pixels of
+by which the page grows (`page_model.js`), the tooltip delay (1 s,
+`DELAY_MS` in `tooltip.js`) and how long after one tooltip the next
+button's comes at once (1 s, `WARM_MS` there), the hold that moves an image (600 ms, with 6 pixels of
 slack, `pen_input.js`), the reach of an image's corner (24 pixels,
 `renderer.js`), the smallest an image can be scaled to (1 cm,
 `page_model.js`), how often a dragged image's place is sent (40 ms,