Restores the work from #1649, which was reverted on main in #1650 to keep
it out of the last release. Content is identical to that merge.
This is a revert of the revert (a8292f5dc) rather than a merge of
kb_git_mvp, deliberately. Merging the branch would make its commits an
ancestor of both dev and main; main's side deleted those files, so the
next merge between the two branches would silently delete them again. A
revert carries the content without the history, so dev and main share no
ancestor that knows about these files, and the eventual dev -> main merge
sees them as added on one side only and keeps them.
Git becomes the source of truth for knowledge base content; Postgres and
pgvector become a derived, rebuildable index. Both switches guarding the
new path default to off: the KNOWLEDGE_STORE_ENABLED env var and the
per-workspace knowledge_store_enabled column, so merging this changes no
runtime behaviour.
Migrations 175 and 176 only add columns and use ADD COLUMN IF NOT EXISTS.
They are already applied on production, where alembic_version was moved
back to 174 during the revert, so they will re-run harmlessly.
Verified on this branch: 0 conflicts against dev, every app.* import in
the restored files resolves, 2251 unit tests pass. The one collection
error (platforms/google_maps) is missing a fixture that is untracked on
both dev and main, and predates this change.
0b34db9d93