Adds :logseq.property.journal/previous and /next (built-in, hidden,
single-cardinality node refs) and maintains them in
logseq.outliner.page/create whenever a new journal page is created.
Filling a gap between two already-linked journals re-links both
neighbors around the new page instead of just appending. A migration
backfills the chain across all existing journal pages ordered by day.
Establishes version control for the personal Logseq DB fork before
starting the server-client architecture migration and domain features
described in docs/agent-guide and the approved implementation plan.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
