Add French anchor productions + bilingual concordance gate

Canadian federal instruments are equally authentic in English and
French (equal authenticity rule); discordance between versions is the
raw material of shared-meaning-rule litigation and no tool checks for
it. The French productions normalize to the SAME keys as their English
twins, so concordance falls out of set intersection: dates (French
months incl. OCR-stripped accents, 1er ordinals), trailing-sign money
('2 250 000 $') and worded multipliers (millions/milliards de dollars,
d'euros), decimal-comma percentages (0,5 %), duration units (jours
ouvrables -> business_day, jours francs -> clear_day, mois kept whole),
statute series (L.R.C.->rsc, L.C.->sc, RLRQ/CQLR->cqlr, ch.->c,
art./par.->s), DORS/TR -> sor/si registers, and French neutral-cite
courts (CSC->scc, CAF->fca, CF/CFPI->fc, CCI->tcc).

bilingualConcordance(en, fr) wraps anchorCoverage into an
english_only/french_only/matched report with a discordance count.
English year form loosened to accept 'R.S.C., 1985' and '(1985)'.
35/35 anchor tests (9 new French + 2 concordance), no English
regressions; full lib suite green except one pre-existing
order-dependent flake in localAssistantTools (passes 8/8 in
isolation, unrelated ToA-bridge test).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_018bhP89cYSdEEjHNPnxacns