fix(pdf-import): 좌표 축소 스케일 제거 — 치수 라벨 실측 정합(R1)

[작업내용] :
- fitAndCenter 가 큰 도면(9.6m 초과)에 scale<1 을 좌표에 곱해 'QLine 길이×10=표시 mm' 불변식을
  깨뜨리던 문제 해소 — 좌표는 실측 그대로 평행이동만 하는 centerOnCanvas 로 대체
- 화면맞춤은 fitViewport 로 분리: 캔버스 중앙 고정 viewportTransform 줌 + canvasZoomState 동기화
  (useCanvasEvent 의 setZoom 은 동일 zoom 값에서 translation 을 보존)

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

src/hooks/pdf-import/usePdfImport.js

@@ -1,6 +1,6 @@
 import { useSetRecoilState, useRecoilValue } from 'recoil'
 import { fabric } from 'fabric'
-import { canvasState } from '@/store/canvasAtom'
+import { canvasState, canvasZoomState } from '@/store/canvasAtom'
 import { outerLineFixState, outerLinePointsState } from '@/store/outerLineAtom'
 import { outlineDisplaySelector } from '@/store/settingAtom'
 import { POLYGON_TYPE } from '@/common/common'
@@ -12,9 +12,9 @@ import { snapNearAxisEdges, cleanSelfIntersectingPolygon } from '@/util/qpolygon
 import * as turf from '@turf/turf'
 
 const MM_PER_CANVAS_UNIT = 10
-const MAX_DIM = 1500
 // useLine.addLine 이 length < 1(=10mm) 라인을 생성하지 않으므로 동일 임계값으로 사전 제거한다.
 const MIN_CANVAS_UNIT_LENGTH = 1
+const VIEWPORT_FIT_RATIO = 0.6 // 화면맞춤 시 캔버스 대비 도면 최대 비율
 const SIMPLIFY_TOLERANCE = 0.5 // canvas unit ≈ 5mm. 직선 위 잉여 정점/미세 엣지 제거(보수적)
 const SNAP_ANGLE_TOL_DEG = 2 // 거의 수평/수직 엣지를 정확히 축정렬로 스냅
 
@@ -50,31 +50,22 @@ const dedupShortEdges = (points) => {
   return out
 }
 
-const fitAndCenter = (points, canvas) => {
+// 좌표에 축소 scale 을 곱하면 'QLine 길이×10 = 표시 mm' 불변식이 깨져 치수 라벨이 실측과 어긋난다.
+// 좌표는 실측 그대로 평행이동만 하고, 화면맞춤은 fitViewport 의 zoom(viewportTransform)으로 분리 처리한다.
+const centerOnCanvas = (points, canvas) => {
   const xs = points.map((p) => p.x)
   const ys = points.map((p) => p.y)
   const minX = Math.min(...xs)
   const minY = Math.min(...ys)
-  const maxX = Math.max(...xs)
+  const width = Math.max(...xs) - minX
-  const maxY = Math.max(...ys)
+  const height = Math.max(...ys) - minY
-  const width = maxX - minX
-  const height = maxY - minY
-
-  const targetWidth = (canvas?.getWidth?.() ?? 1000) * 0.6
-  const targetHeight = (canvas?.getHeight?.() ?? 1000) * 0.6
-  const maxAllowed = Math.min(MAX_DIM, Math.max(targetWidth, targetHeight))
-
-  let scale = 1
-  if (width > maxAllowed || height > maxAllowed) {
-    scale = Math.min(maxAllowed / width, maxAllowed / height)
-  }
 
   const cx = (canvas?.getWidth?.() ?? 1000) / 2
   const cy = (canvas?.getHeight?.() ?? 1000) / 2
 
   return points.map((p) => ({
-    x: cx + (p.x - (minX + width / 2)) * scale,
+    x: cx + (p.x - (minX + width / 2)),
-    y: cy + (p.y - (minY + height / 2)) * scale,
+    y: cy + (p.y - (minY + height / 2)),
   }))
 }
 
@@ -106,6 +97,7 @@ export function usePdfImport() {
   const canvas = useRecoilValue(canvasState)
   const setOuterLinePoints = useSetRecoilState(outerLinePointsState)
   const setOuterLineFix = useSetRecoilState(outerLineFixState)
+  const setCanvasZoom = useSetRecoilState(canvasZoomState)
   const isOutlineDisplay = useRecoilValue(outlineDisplaySelector)
   const { addLine } = useLine()
   const { swalFire } = useSwal()
@@ -168,6 +160,29 @@ export function usePdfImport() {
     })
   }
 
+  // 도면이 화면보다 크면 캔버스 중앙 고정 줌으로 화면맞춤한다. canvasZoomState 를 함께 동기화하면
+  // useCanvasEvent 의 setZoom(동일 zoom 값) 은 translation 을 보존하므로 중앙 정렬이 유지된다.
+  const fitViewport = (points) => {
+    const xs = points.map((p) => p.x)
+    const ys = points.map((p) => p.y)
+    const width = Math.max(...xs) - Math.min(...xs)
+    const height = Math.max(...ys) - Math.min(...ys)
+
+    const targetWidth = canvas.getWidth() * VIEWPORT_FIT_RATIO
+    const targetHeight = canvas.getHeight() * VIEWPORT_FIT_RATIO
+
+    let zoomPercent = 100
+    if (width > targetWidth || height > targetHeight) {
+      zoomPercent = Math.max(1, Math.floor(Math.min(targetWidth / width, targetHeight / height) * 100))
+    }
+    const zoom = zoomPercent / 100
+
+    const cx = canvas.getWidth() / 2
+    const cy = canvas.getHeight() / 2
+    canvas.setViewportTransform([zoom, 0, 0, zoom, cx * (1 - zoom), cy * (1 - zoom)])
+    setCanvasZoom(zoomPercent)
+  }
+
   const applyOuterline = async (mmPoints, options = {}) => {
     if (!canvas) {
       logger.warn('[usePdfImport] canvas 가 준비되지 않았습니다.')
@@ -202,7 +217,7 @@ export function usePdfImport() {
       return false
     }
 
-    canvasPoints = fitAndCenter(canvasPoints, canvas)
+    canvasPoints = centerOnCanvas(canvasPoints, canvas)
     canvasPoints = ensureCounterClockwise(canvasPoints)
 
     const proceed = async () => {
@@ -218,6 +233,7 @@ export function usePdfImport() {
       canvas.outerLineFix = true
       setOuterLineFix(true)
 
+      fitViewport(closedPoints)
       canvas.renderAll()
     }