fzf-pick prop set's key and value when not supplied
tsk prop set <id> — fzf-pick key from existing keys, then value
from existing values for that key
tsk prop set <id> <key> — fzf-pick value only
tsk prop set <id> <key> <v> — direct (existing behavior)
tsk prop set <id> -l — also include URLs and [[tsk-N]] refs parsed
from the task body as value candidates
The fzf list always carries a `<new>` sentinel so the user can type a
fresh string at a prompt instead of picking from history. Helpful when
seeding a new property name or a value that hasn't been used before.
Tests cover the underlying candidate queries (keys, values-for-key,
body candidates) on both backends; the fzf interaction itself remains
manual.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>