Merge Down from main into dev: reconcile today's release-rehearsal hotfixes.
All 19 files here are fixes made directly in main today while exercising
the release process for real (revnumber/revdate bumps, ReleaseNotes'
2026.1 GA section, gen_file_format_check.sh's stale-path/VersionID fix,
gen_script_man_pages.sh's missing-script/stale-path fix,
preview_changes_and_update_version.sh's first-release Version-add fix,
and ReleaseProcessOverview.md's several corrections). Verified these are
exactly today's own edits with nothing else touching these files
concurrently, so accept-theirs (main's content) is correct and safe here,
not a blind resolve.
Agent: Claude Code, Model: Claude Sonnet 5 (claude-sonnet-5), operating as bot_Claude_Anthropic.