`ImageResizer.resizeImageIfNeeded` created a fresh `BitmapFactory.Options` and passed it to `calculateSampleSize`, which read `options.outWidth` and `options.outHeight`. That object had never been used for a decode, so both were 0 and the sample size was always 1: every resize with `maxWidth` or `maxHeight` decoded the full-size bitmap (about 48 MB for a 12 MP photo) before scaling it down. The original dimensions were already read by `readFileDimensions`, into a different `Options`.

This PR passes those original dimensions to `calculateSampleSize` instead. The sample size stays the largest power of two that still decodes at least the target size, so the output dimensions are unchanged.

The new `onResizeImageIfNeeded_whenDownscaling_shouldSubsampleFromOriginalSize` test resizes a 12x7 image to a width of 3 and checks the pixel decode uses `inSampleSize == 2` (before the fix it was 1) and that the output is still 3x2. This is not a regression: subsampling has never taken effect, since `inSampleSize` has been 1 from when it was introduced in #3423, and before that the full image was decoded too.

Fixes https://github.com/flutter/flutter/issues/193036

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