fix(overlay): Photos-ready dims follow tape, not wood MAR

After rotateCalibration, map tape tick A→B through bakeTiltTransform into
baked cal coords, orient overlay bbox with orientedRect(..., tapeAngle), and
pass optional axis into buildOverlayPlan so length || tape and widths ⊥ tape.

frontend/src/capture/session.ts

@@ -10,7 +10,7 @@ import { measure } from '../measure/measure';
 import { orientedRect } from '../geometry/rect';
 import { encodeInventoryPng, type InventoryInput } from '../png/inventory';
 import { encodeOverlayPng, type EncodeOverlayInput } from '../png/overlay';
-import { rotateCalibration } from '../png/rotateCal';
+import { bakeTiltTransform, rotateCalibration } from '../png/rotateCal';
 import { decodeOrientedBitmap } from '../decodeOrientedBitmap';
 import { clampTiltDeg, defaultTape, tapeEndpoints, type TapeTransform } from './tapeGeometry';
 import { getCropFill } from '../settings/cropFill';
@@ -636,19 +636,37 @@ export function createCaptureSession(opts: SessionOpts = {}): CaptureSession {
       // #63: second copy of the calibration inventory PNG with dimension overlays.
       // Keep clean inventoryPng untouched; never stash overlay into batchApply[cal].
       // Overlay uses the same baked orientation as the clean cal PNG (#99 scope).
+      // Length / width directions follow the tape (not wood MAR): map tick A→B
+      // through the same bake as rotateCal, then orient the overlay bbox to that.
       let overlayBlob: Blob;
       try {
+        const preEp = axis.tape.spanPx > 0
+          ? tapeEndpoints(axis.tape, source.widthPx, source.heightPx)
+          : null;
+        const bakeXform = bakeTiltTransform(source.widthPx, source.heightPx, axis.tape.tiltDeg);
+        let overlayBbox = calMask.bbox;
+        let overlayAxis: { start: [number, number]; end: [number, number] } | undefined;
+        if (preEp && preEp.spanPx > 0) {
+          const start = bakeXform.mapPoint(preEp.start[0], preEp.start[1]);
+          const end = bakeXform.mapPoint(preEp.end[0], preEp.end[1]);
+          const dx = end[0] - start[0];
+          const dy = end[1] - start[1];
+          const angleDeg = ((Math.atan2(dy, dx) * 180) / Math.PI + 180) % 180;
+          overlayBbox = orientedRect(calMask.bbox, angleDeg);
+          overlayAxis = { start, end };
+        }
         overlayBlob = await encodeOverlay({
           inventoryPng: pngBlob,
           bitset: calMask.bitset,
           widthPx: calSource.widthPx,
           heightPx: calSource.heightPx,
-          bbox: calMask.bbox,
+          bbox: overlayBbox,
           scale: base.scale,
           lengthIn: eighthsToIn(lengthEighths),
           lengthLabel: fmtEighths(lengthEighths),
           slabBounds: calMask.slabBounds,
           source: calSource,
+          axis: overlayAxis,
         });
       } catch {
         // Deterministic tests may inject a non-decodable inventory blob; still