max / quasi

0.79.0: a hierarchy of rows, said as depth and a disclosure `ccaa7e4b`. `Row` and `Cells` gain `depth` and `open`: a hierarchy is a flat list of rows each saying how deep it sits, not rows holding rows, so a renderer that has never heard of either still draws the list it drew before with nothing missing. `folded` reads which rows a shut branch covers, in the description layer, so the three renderers cannot disagree about what a branch holds. `Outline` is the trait both containers answer it through, and `key` is how a renderer holding the reader's own folds names a branch. The gesture is the renderer's, on `Region::showing_at_most_one`'s rule: `open` is where the outline starts, not where it stays, so folding asks the app nothing. The webview keeps every row in the document and hides what a shut branch covers, with `outline.js` doing the press; the terminal answers Left and Right and keeps the folds in its view; egui draws a chevron beside the label and never under it.