Merge branch '5_x'

Brings in the 5.0 feature set: the markdown-patch 2.0 engine (JSON
PATCH instructions, URL path-element targeting, raw-content mode, the
nested document map with version tokens), native periodic-notes
settings, trash-by-default deletes, the COPY method, rendered HTML
reads, unresolvedLinks metadata, and the declarative settings tab.

# Conflicts:
#	.claude/settings.json