Removes the on-mount `void userContextStore.ensureDoc()` race from
ContextOverview / ContextInterview / ContextFreeform. After F4 the
server creates the singleton at /register time; the first sync pull
lands it before the UI can race.
The internal logic survives as `getOrCreateLocalDoc()` — a private
fallback for the brand-new client whose pull hasn't caught up yet.
First user mutation (setField, setFreeform, …) inserts an empty
local doc with origin='user' on the field-meta map. The F2
conflict-gate then makes sure the server's origin='system' bootstrap
row never silently overwrites the user's local edits — they land in
the conflict toast like a real edit-race would.
`kontextStore.ensureDoc()` is intentionally kept (per-Space, not
per-user; F4 didn't bootstrap it). Its removal will follow once
Space-creation gains its own bootstrap hook.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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