Subcommand dispatch is now help-driven instead of substring-matching
"REVSET", so multi-level subcommands (`tag set`, `bookmark move`, …)
and non-`-r` revset flags (`--to`) work, and pre-supplied revset
flags bypass the picker instead of being double-injected.
Picker now renders jj's real graph (merge connectors and all). Cursor
and filter skip decorative connector rows; hint row drops trailing
key/label pairs to fit a single line on narrow terminals; cursor
arrow glyphs changed to ●──▶.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>