fix(mapper): drop the "wall location → vertical" guard that broke cert 000516

Slice f68cea27 (re-homed here as 97f44b53) added a guard to
_is_elmhurst_roof_window — "a window lodged on a wall is vertical by
definition" — to keep 001431's two "Double pre 2002" External-wall units in
the vertical sap_windows list for the Modelling draught-proofing count. But
that guard fires on the §11 `location` string, which is an unreliable
lodging artifact: every one of cert 000516's six §11 rows reads "External
wall", and only the U-value separates the five vertical panes (U 2.8) from
the one genuine rooflight (U 3.1, area 1.18, lifted to 3.40 by the Table 24
lookup). Elmhurst's own worksheet routes that U 3.1 "External wall" unit
through (27a) Roof Windows — so location is NOT a vertical signal and the
U > 3.0 backstop (RdSAP 10 §3.7.1) is what matches the worksheet.

Removing the guard restores both 000516 pins
(test_summary_000516_full_chain_sap_matches_worksheet_pdf_exactly,
test_from_elmhurst_site_notes_matches_hand_built_000516) with no other
regression (2879 pass; the lone test_total_floor_area failure is
pre-existing on the branch base, unrelated to window classification).

The extractor half of 97f44b53 (capturing the standalone "BFRC data" §11
row) is retained — it is independent of this classifier and harmless here.
The 001431 Modelling draught-proofing count must instead include roof
windows (the draught_proofed-on-SapRoofWindow approach noted in the glazing
handover), which is feature/bill-derivation's front, not this branch.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

datatypes/epc/domain/mapper.py

@@ -4116,14 +4116,14 @@ def _is_elmhurst_roof_window(
         _ELMHURST_BP_ROOF_TYPES_WITH_ROOFLIGHTS
     ):
         return True
-    # A window lodged on a wall is vertical by definition. The U-value
-    # backstop below only catches skylights whose location/BP gives no
-    # roof signal; without this guard a high-U *wall* window (e.g. an old
-    # "Double pre 2002" unit at U 3.1 / 3.4) is mis-routed to the roof-
-    # window list on U-value alone — cert 001431 §11 lodges two such
-    # External-wall windows that must remain vertical `sap_windows`.
-    if "wall" in (w.location or "").lower():
-        return False
+    # U > 3.0 backstop — Elmhurst routes high-U "Double pre 2002" units
+    # through the worksheet's (27a) Roof Windows line regardless of the
+    # lodged "External wall" location, which is a §11 lodging artifact
+    # (cert 000516's W6 is lodged "External wall" yet scored via (27a)).
+    # The location string is therefore NOT a reliable vertical signal:
+    # all six of 000516's §11 rows read "External wall", and only U
+    # separates the five vertical (2.8) panes from the one rooflight
+    # (3.1). Matching the worksheet means trusting U here, not location.
     return w.u_value > _ELMHURST_ROOF_WINDOW_U_THRESHOLD