This reverts commit 366f9c18a, keeping the git-native knowledge base in
dev until the issues queued for the next release are fixed.
Nothing shipped by that merge was reachable in production: git-native
behaviour needs both the KNOWLEDGE_STORE_ENABLED env (default FALSE) and
a per-workspace column (default false), so reverting changes no runtime
behaviour.
Migrations 175 and 176 stay applied in production; alembic_version is
moved back to 174 by hand so this tree's upgrade is a no-op. Both
revisions only add columns, and they use ADD COLUMN IF NOT EXISTS, so
re-landing this work re-applies them harmlessly.
a8292f5dcc