SystemsLab 168.0.0

Added

Notebooks can mention workspaces and notebooks, from the @ picker or with a /w/<id> or /notebook/<id> link. A link to a workspace by slug becomes a mention of it by id when the notebook is saved, so it keeps working after the slug changes.
Notebook API responses have an ETag, and PATCH and block edits accept If-Match. A conditional change fails with a 412 unless the notebook is still at that ETag, including when it is a retry of a change that was already made.

The notebook editor now edits the notebook's markdown directly, styling each line as it renders, with Edit, Split and Preview layouts. Charts and KPI tables are drawn in place and edited in a dialog, / and @ insert blocks and mentions, "Done" is now "Save", and Ctrl+S saves.

Fixed the notebook editor sometimes overwriting another user's change when it retried a save whose response was lost.
Fixed the metrics page failing to load when a line chart and its heatmap with the same title both had no data, as on a very short recording.