feat(frame): give ROTATE quarter turns plus a fine straighten

src/utils/skiaImage.ts

@@ -25,3 +25,44 @@ export function rotateSkImage90(image: SkImage | null): SkImage | null {
   canvas.drawImage(image, 0, 0);
   return surface.makeImageSnapshot() ?? image;
 }
+
+// Fine rotation about the centre (the FRAME tab's STRAIGHTEN), keeping the
+// original pixel dimensions: the content is scaled up just enough that the
+// rotated rectangle still covers the frame, so no empty corner shows. The
+// scale is the axis-aligned wrap of the counter-rotated frame — slightly
+// conservative, which crops a hair more rather than leaking a corner.
+// ponytail: one offscreen surface per call, same trade as rotateSkImage90.
+export function rotateSkImageBy(image: SkImage | null, degrees: number): SkImage | null {
+  if (!image) return null;
+  const w = image.width();
+  const h = image.height();
+  if (!(w > 0 && h > 0)) return null;
+  if (!degrees) return image;
+  const rad = (degrees * Math.PI) / 180;
+  const cos = Math.abs(Math.cos(rad));
+  const sin = Math.abs(Math.sin(rad));
+  const k = Math.max((w * cos + h * sin) / w, (w * sin + h * cos) / h);
+  const surface = Skia.Surface.Make(w, h);
+  if (!surface) return image; // keep the unrotated photo on allocation failure
+  const canvas = surface.getCanvas();
+  canvas.clear(Skia.Color('transparent'));
+  canvas.translate(w / 2, h / 2);
+  canvas.rotate(degrees, 0, 0);
+  canvas.scale(k, k);
+  canvas.drawImage(image, -w / 2, -h / 2);
+  return surface.makeImageSnapshot() ?? image;
+}
+
+// The whole FRAME-tab photo orientation in one call: the quarter turn first
+// (rotateSkImage90 swaps the pixel dimensions, which then propagates through
+// every consumer unchanged), then the fine STRAIGHTEN on top of it.
+export function applyPhotoRotation(
+  image: SkImage | null,
+  quarter = 0,
+  straighten = 0
+): SkImage | null {
+  let out = image;
+  for (let i = 0; i < Math.round(quarter / 90) % 4; i++) out = rotateSkImage90(out);
+  if (straighten) out = rotateSkImageBy(out, straighten);
+  return out;
+}