keymap.ts lists every key with its context, action and help line.
actions.ts holds what each one does, typed against the table so a key
without an action, or an action without a key, does not compile.
modes.ts stacks the contexts (always > sheet > drawer > workspace >
writing > focused tile > special > global) and writes the two-key
pending logic once. App.svelte's 480-line onkeydown is now one call.
Help, the panel footers (a shared Keys component), the rail's keycaps
and Commands.md all read the table; the wiki gains the card and
scratchpad key tables.
One fix on the way: Ctrl-S in the editor no longer saves twice, which
could make the second save fail as "changed somewhere else".
