Drop committed reference-data.sqlite binary + stop exporting users PII (atomic removal)

Fleet decision bs-mr4mjr68vld (4/4 unanimous): drop the committed binary db/reference-data.sqlite. ATOMIC single commit — (1) git rm db/reference-data.sqlite, (2) gitignore it, (3) remove 'users' from export-db.py REFERENCE_VIEWS (it exports 12 real emails+names = PII — must never be in a committed artifact per adopted hard clause), (4) optional generated-text lookup dump via export-db.py if we want offline vocab, (5) re-point or retire the .gitpush-pre freshness gate (it keys on schema/migration mtime, is false-currency + can block pushes) at schema.md, (6) fix role-doc refs (agents/.role/db-ayudarg-role.md + db/README.md) + any stale db/CLAUDE.md desc, (7) KEEP schema.md committed. Else next schema push hard-errors. SEPARATE + Elazar-gated: history-scrub (git filter-repo force-push) to purge the 12 PII rows already in git history — force-pushes shared 4-agent repo + solo clone; NOT part of this WI, held for Elazar go/no-go. db-ayudarg-cc pairs on export-db.py + gate; coder executes the commit+push.