v1.48.0: the canvas is always square, the plan is centred inside it

A space carried an aspect ratio, and coordinates were normalised against it: x
by the width, y by the height. Every geometric question therefore depended on a
per-space number, and picking a canvas orientation was a decision the user had
no reason to make. The render space is now NORM_W x NORM_W and a plan image is
fitted into it by its OWN ratio, centred — wide plans get margins above and
below, tall ones at the sides.

Migration (geometry_migration.py, pure and unit-tested) runs once at setup under
the write lock. Nothing about a drawing changes: the old box is padded out to a
square and every coordinate re-expressed against it — rooms as rects and
polygons, openings and their lengths, decor, view_box, and the marker positions
in the separate layout store. In render units it is a uniform scale plus an
offset, so angles and proportions are exact. cell_cm is scaled for tall plans,
because the grid pitch is a fraction of the width: without it a wall would
measure less than it does.

 is now dropped by the schema rather than accepted — a stale tab sending
it would be sending coordinates from the old normalisation too, and honouring
the field would not make them right.

The demo fixture was migrated with the same transform, so the smokes exercise
the new geometry rather than a square-native fake; six of them needed their
render-space helpers updated and one its click coordinates.

Not released — dev only, per the owner's instruction.

src/space-geometry.ts

@@ -6,16 +6,32 @@
 import { declump, contentUrl } from './logic';
 import type { ServerConfig, SpaceModel, RoomCfg, DevItem } from './types';
 
-export const NORM_W = 1000; // width of the render space for normalized configs
+export const NORM_W = 1000; // side of the render space — the canvas is square
+
+/**
+ * Where a plan image sits inside the square canvas (v1.48.0).
+ *
+ * The canvas has no proportions of its own any more; the image keeps its own
+ * and is centred, so a wide plan gets margins above and below and a tall one
+ * gets them at the sides. `ratio` is the image's width/height; without it we
+ * assume square, which is only ever a brief guess before the file loads.
+ */
+export function fitInSquare(ratio: number | null | undefined, side: number) {
+  const r = Number(ratio);
+  const a = Number.isFinite(r) && r > 0 ? r : 1;
+  const w = a >= 1 ? side : side * a;
+  const h = a >= 1 ? side / a : side;
+  return { x: (side - w) / 2, y: (side - h) / 2, w, h };
+}
 
 export type Pt = { x: number; y: number };
 export type Layout = Record<string, { s?: string; x: number; y: number } | undefined>;
 
-/** Build render-space models (NORM_W × NORM_W/aspect) from a server config. */
+/** Build render-space models (NORM_W × NORM_W) from a server config. */
 export function spaceModels(cfg: ServerConfig | null): SpaceModel[] {
   if (!cfg || !Array.isArray(cfg.spaces)) return [];
   return cfg.spaces.map((s: any) => {
-    const H = NORM_W / s.aspect;
+    const H = NORM_W; // square canvas
     const scale = (r: any): RoomCfg => ({
       id: r.id,
       name: r.name,
@@ -35,7 +51,7 @@ export function spaceModels(cfg: ServerConfig | null): SpaceModel[] {
       id: s.id,
       title: s.title,
       vb: [s.view_box[0] * NORM_W, s.view_box[1] * H, s.view_box[2] * NORM_W, s.view_box[3] * H],
-      bg: s.plan_url ? { href: contentUrl(s.plan_url), x: 0, y: 0, w: NORM_W, h: H } : null,
+      bg: s.plan_url ? { href: contentUrl(s.plan_url), ...fitInSquare(s.plan_aspect, NORM_W) } : null,
       rooms: (s.rooms || []).map(scale),
     } as SpaceModel;
   });
@@ -91,8 +107,7 @@ export function defaultPositions(devs: DevItem[], model: SpaceModel, iconPct: nu
 export function markerPos(d: DevItem, layout: Layout, cfg: ServerConfig, defPos: Record<string, Pt>, model: SpaceModel): Pt {
   const saved = layout[d.id];
   if (saved && saved.s === d.space) {
-    const aspect = cfg.spaces.find((x: any) => x.id === d.space)?.aspect || 1;
-    return { x: saved.x * NORM_W, y: saved.y * (NORM_W / aspect) };
+    return { x: saved.x * NORM_W, y: saved.y * NORM_W };
   }
   if (defPos[d.id]) return defPos[d.id];
   const vb = model.vb;
@@ -103,8 +118,7 @@ export function markerPos(d: DevItem, layout: Layout, cfg: ServerConfig, defPos:
 export function labelPos(r: RoomCfg, spaceId: string, layout: Layout, cfg: ServerConfig): Pt {
   const saved = layout['rl_' + (r.id || '')];
   if (saved && saved.s === spaceId) {
-    const aspect = cfg.spaces.find((x: any) => x.id === spaceId)?.aspect || 1;
-    return { x: saved.x * NORM_W, y: saved.y * (NORM_W / aspect) };
+    return { x: saved.x * NORM_W, y: saved.y * NORM_W };
   }
   const c = roomCenter(r);
   return { x: c[0], y: c[1] };