perf: reuse visible room contours for PDF

Issue: #53
User-Visible: no

src/houseplan-card.ts

@@ -10688,6 +10688,8 @@ export class HouseplanCard extends LitElement {
     for (const [id, asset] of this._decorAssets) {
       decorAssets.set(id, { url: this._display(asset.url), mime: asset.mime });
     }
+    const sharedWallGeometry = this._wallUnionGeometry();
+    const openCuts = this._openCuts();
     return runtime.render({
       config: this._serverCfg,
       rawSpace,
@@ -10699,7 +10701,10 @@ export class HouseplanCard extends LitElement {
       hass: this.hass,
       backdropUrl: space.bg ? this._display(space.bg.href) : '',
       decorAssets,
-      sharedWallGeometry: this._wallUnionGeometry(),
+      sharedWallGeometry,
+      resolveInnerContour: (roomId) => this._innerRoomContour(
+        space, roomId, openCuts, sharedWallGeometry?.roomGeom, sharedWallGeometry?.multiWallNodes,
+      ),
       t: (key, vars) => this._t(key as I18nKey, vars),
       toast: (message) => this._showToast(message),
       close: () => { this._pdfDialog = false; this.requestUpdate(); },

src/pdf/hp-pdf-dialog.ts

@@ -18,6 +18,7 @@ export interface PdfDialogContext {
   backdropUrl: string;
   decorAssets: ReadonlyMap<string, PdfAssetReference>;
   sharedWallGeometry?: PdfSharedWallGeometry | null;
+  resolveInnerContour?: (roomId: string) => number[][] | null | undefined;
   t: (key: string, vars?: Record<string, string | number>) => string;
   toast: (message: string) => void;
   close: () => void;

src/pdf/pdf-scene.ts

@@ -68,6 +68,8 @@ export interface PdfSceneInput {
   rasters?: readonly PdfRasterPlacement[];
   /** The exact structural pass already used by the visible card. */
   sharedWallGeometry?: PdfSharedWallGeometry | null;
+  /** The visible card's per-room clean-floor cache, resolved only when dimensions are requested. */
+  resolveInnerContour?: (roomId: string) => number[][] | null | undefined;
 }
 
 const MM = 72 / 25.4;
@@ -210,10 +212,11 @@ export function buildPdfPage(input: PdfSceneInput): PdfPage & { scale: number }
   if (input.options.dimensions) for (const room of input.space.rooms) {
     const original = roomPoly(room);
     if (!original) continue;
-    dimensionContours.set(room, room.id ? innerContourForRoom(
+    const shared = room.id ? input.resolveInnerContour?.(room.id) : undefined;
+    dimensionContours.set(room, room.id ? (shared === undefined ? innerContourForRoom(
       input.space.rooms, room.id, built.walls, built.zero.contour, GRID_STEP_N,
       built.cellCm, GRID_PITCH, NORM_W, built.geometry.roomGeom, built.geometry.multiWallNodes,
-    ) || original : original);
+    ) : shared) || original : original);
   }
   const architectureRings = built.geometry.status === 'failed-core'
     ? input.space.rooms.map((room) => roomPoly(room) || []).filter((ring) => ring.length)