Atomic-remove committed db/reference-data.sqlite binary (fleet decision bs-mr4mjr68vld, 4/4)

Fleet brainstorm bs-mr4mjr68vld ruled 4/4: committed binary reference-data.sqlite = a stale cache of the live-SSOT prod DB, DROP it. Pluto is FILE-VERIFIED PII-CLEAN (36KB, lookupOptions(132)+_meta only, zero user/roster) so this is a clean go-forward drop, NO history-scrub needed. ATOMIC single commit: (1) git rm --cached db/reference-data.sqlite + add to .gitignore; (2) RE-POINT the .gitpush-pre.sh freshness gate from the sqlite mtime to schema.md (keep the 'did you re-export after a schema/migration change' tripwire in text form — do NOT bare-retire, the schema-freshness value is real; just stop keying it on the binary); (3) keep db:export generating the sqlite LOCALLY for on-demand agent lookups (gitignored) — optionally also emit a text .tsv/.sql lookup dump per the fleet 'generated text' preference; (4) FIX the stale db/CLAUDE.md:9 description that falsely claims the mirror holds users/roles/periodos/comisiones/assignments — real export is lookupOptions-only; (5) update the 3 role-doc refs (db/audit/dev) that point at the committed file. All in ONE commit or the next schema push hard-errors. Owner: coder (owns .gitpush-pre.sh + push lane); db consulted on the db:export text-dump + the correct db/CLAUDE.md mirror-scope wording. Keep schema.md committed unchanged.