274: drop 紅葉山橋, fix オロロップ橋 and 下福山橋, re-timed lyric

紅葉山橋 is not on R274. The full Reiwa 8 bridge register lists it once, on
国道452号 (100.1 m, PC, 1989), just up R452 from the 紅葉山交差点. It had come
in through the OSM corridor sweep, which selected by distance rather than by
road — hence the only `bridge (structure)` kind in the roster and its 533 m
offset. An audit of all 53 roster structures against every route in the three
registers found no other stray.

オロロップ橋 moves to 78.31 km from the author's Google pin, on the 221 m OSM
bridge way that matches the register's 205.9 m. 下福山橋 moves to 78.03, the
104 m way. Both had been displaced by using the オロロップ沢川 stream crossing at
77.05 as an anchor; the stream and the bridge are 1.2 km apart. The sung order
ペンケ → 下福山 → オロロップ → 福山 was already right.

Lyric re-timed by the author with 紅葉山橋 removed; 274.md and 274.lrc match.
Lyric index regenerated: 97 lines, 98 rows, zero backward km steps.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

wip/274/274.md

@@ -45,7 +45,6 @@ Codename `Yuubari 2` but I've decided that this will be more about Route 274. Th
 紅葉山郵便局
 紅葉山神社
 セイコーマートもみじやま店
-紅葉山橋
 紅楓橋
 ポン久留喜橋
 久留喜橋