chore: Switch stackable-operator to smooth-operator branch

Point stackable-operator at the smooth-operator branch (via [patch]) to gain
access to the v2:: framework modules, in preparation for removing the
product-config dependency. Bump dependencies (cargo update) to satisfy the
branch's snafu >=0.9.1 requirement.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: maltesander