feat v1.37.0: open boundaries (virtual walls)

- room.open_to symmetric links; 'Open boundary' plan tool toggles the
  shared wall pair under the click (sharedBoundary collinear-overlap
  math + distToSegment pull, same as Split); dashed rendering with an
  amber hot state while the tool is active; Esc -> Draw
- glow: the clip becomes the transitive open zone (openZoneOf BFS,
  either-direction links) + door sectors from the zone's outer walls
- model rooms carry open_to; backend ROOM_SCHEMA open_to: [str]
- +3 unit tests (104), smoke_openwall.mjs (8 checks); docs same-commit

src/i18n/en.json

@@ -293,5 +293,10 @@
   "marker.controls_filter": "Search lights and switches…",
   "info.controls": "Controls",
   "marker.glow_radius_label": "Glow radius (light-sources fill)",
-  "marker.glow_radius_hint": "empty = default from general settings"
+  "marker.glow_radius_hint": "empty = default from general settings",
+  "markup.openwall": "Open boundary",
+  "title.markup_openwall": "Open boundary — click a wall shared by two rooms to make it virtual: light flows through, the line turns dashed. Click again to close it.",
+  "toast.openwall_pick": "Click a wall shared by two rooms",
+  "toast.openwall_opened": "Boundary “{a}” ↔ “{b}” is now open",
+  "toast.openwall_closed": "Boundary “{a}” ↔ “{b}” is closed again"
 }

src/i18n/ru.json

@@ -293,5 +293,10 @@
   "marker.controls_filter": "Поиск ламп и выключателей…",
   "info.controls": "Управляет",
   "marker.glow_radius_label": "Радиус свечения (заливка «Свет по источникам»)",
-  "marker.glow_radius_hint": "пусто = по умолчанию из общих настроек"
+  "marker.glow_radius_hint": "пусто = по умолчанию из общих настроек",
+  "markup.openwall": "Открытая граница",
+  "title.markup_openwall": "Открытая граница — клик по общей стене двух комнат делает её условной: свет проходит насквозь, линия становится пунктирной. Повторный клик закрывает.",
+  "toast.openwall_pick": "Кликните по стене, разделяющей две комнаты",
+  "toast.openwall_opened": "Граница «{a}» ↔ «{b}» теперь открыта",
+  "toast.openwall_closed": "Граница «{a}» ↔ «{b}» снова закрыта"
 }