* M6: FigJam .jam files open like .fig files (#1342)
A .jam is the same archive as a .fig (its canvas header reads fig-jam.), which the .fig reader already took; File > Open and its filter, drag and drop, file.import and the command line now take .jam too, and the home screen shows its thumbnail. FigJam layers come in as the .fig reader makes them (stickies and shapes with text as frames with their generated layers, other FigJam layers as frames or vectors with a note, unknown types left out with a note). Tests use a synthetic fig-jam. canvas and a .jam made from our own export.
* M12: a FigJam .jam file opens as a board (#1342)
The .fig reader marks a canvas with FigJam's fig-jam. header as FileKind::Board, so a .jam opens with the board toolbar, the dot grid and the board panels and saves as a board; a .fig stays a design file, and importing a .jam into an open file leaves its kind alone. Its objects stay ordinary layers (frames and vectors with the existing import notes). Builds on the .jam opening branch (#1586).
`file.open` on a path already open in a tab switched to it and returned
its index, even when another process had changed the file since, so the
caller kept looking at the old copy with nothing saying so (#997). The
tab's disk stamp from #1330 (`DocState::on_disk`) now tells:
- the result says `stale: true` when the file on disk differs from what
the tab read or last saved;
- `reload: true` reads the file again into the tab, as Revert to saved
does (refused while the tab has unsaved changes or is in a live
session), and the result says `reloaded: true`.
MCP's `open_file` takes `reload` and passes it on.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>