laws sections: dot-form labels, fr surface names, pseudo-label convention

Laws vet decomposed the 17.5pp full-corpus recovery gap; the real
detector gaps are now closed, measured before/after per set (fixed sets
scanned in FULL, controls reservoir-sampled seed 47):

1. SECTION_MARK_RE_EXT accepts the NT/PE dot-form drafting convention
   ("1. There is established...", "2.(1) In this section") and NB's
   markdown-heading decimal rules ("### 61.01 Enforcement of Orders"):
     LEGISLATION-NT  rec 0.029 -> 0.985   prec 0.754 -> 0.989
     LEGISLATION-PE  rec 0.037 -> 0.986   prec 0.834 -> 0.987
     REGULATIONS-NT  rec 0.102 -> 0.996   prec 0.272 -> 0.734
     REGULATIONS-PE  rec 0.109 -> 0.991   prec 0.355 -> 0.770
     REGULATIONS-NB  rec 0.837 -> 0.994   prec 0.898 -> 0.943

2. named_heading_labels keeps the heading's surface language (fr oracles
   key 'Annexe I'; the old fr->en translation never matched anything) and
   _NAMED_HEAD_RE learns Formulaire:
     REGULATIONS-YT  rec 0.915 -> 0.993 (prec 0.639 -> 0.611, oracle-
     omission set; dual-emission variant measured worse at 0.582 and was
     rejected)

3. sweep law branch: single-pseudo-label oracles (Order / Ordonnance /
   Proclamation - 1,218 REG-FED + 582 REG-NL unsectioned instruments)
   are a provider naming convention, not a recovery target; recorded as
   single_instrument, excluded from recovery scoring.

Controls unchanged or better: LEGISLATION-FED rec .887->.902 prec
.987->.994, ON .947->.964/.983, BC identical, REGULATIONS-FED
.897->.942/.910->.934, REGULATIONS-NL rec identical prec -0.004.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_012AgUm5EcRKbT3duVFMbrQD