Fill mean and stdDev tails with zeros for HAL branch in meanStdDevopencv#25789as it's done for other branches.See details athttps://github.com/opencv/opencv/wiki/How_to_contribute#making-a-good-pull-request- [x] I agree to contribute to the project under Apache 2 License.- [x] To the best of my knowledge, the proposed patch is not based on a code under GPL or another license that is incompatible with OpenCV- [x] The PR is proposed to the proper branch- [ ] There is a reference to the original bug report and related work- [ ] There is accuracy test, performance test and test data in opencv_extra repository, if applicable      Patch to opencv_extra has the same branch name.- [ ] The feature is well documented and sample code can be built with the project CMake

Fill mean and stdDev tails with zeros for HAL branch in meanStdDevopencv#25789as it's done for other branches.### Pull Request Readiness ChecklistSee details athttps://github.com/opencv/opencv/wiki/How_to_contribute#making-a-good-pull-request- [x] I agree to contribute to the project under Apache 2 License.- [x] To the best of my knowledge, the proposed patch is not based on a code under GPL or another license that is incompatible with OpenCV- [x] The PR is proposed to the proper branch- [ ] There is a reference to the original bug report and related work- [ ] There is accuracy test, performance test and test data in opencv_extra repository, if applicable      Patch to opencv_extra has the same branch name.- [ ] The feature is well documented and sample code can be built with the project CMake

… on ARM.

Added flag to GaussianBlur for faster but not bit-exact implementationopencv#25792Rationale:Current implementation of GaussianBlur is almost always bit-exact. It helps to get predictable results according platforms, but prohibits most of approximations and optimization tricks.The patch converts `borderType` parameter to more generic `flags` and introduces `GAUSS_ALLOW_APPROXIMATIONS` flag to allow not bit-exact implementation. With the flag IPP and generic HAL implementation are called first. The flag naming and location is a subject for discussion.Replacesopencv#22073Possibly related issue:opencv#24135See details athttps://github.com/opencv/opencv/wiki/How_to_contribute#making-a-good-pull-request- [x] I agree to contribute to the project under Apache 2 License.- [x] To the best of my knowledge, the proposed patch is not based on a code under GPL or another license that is incompatible with OpenCV- [x] The PR is proposed to the proper branch- [ ] There is a reference to the original bug report and related work- [x] There is accuracy test, performance test and test data in opencv_extra repository, if applicable      Patch to opencv_extra has the same branch name.- [ ] The feature is well documented and sample code can be built with the project CMake

HAL for dot product addedopencv#25936See details athttps://github.com/opencv/opencv/wiki/How_to_contribute#making-a-good-pull-request- [x] I agree to contribute to the project under Apache 2 License.- [x] To the best of my knowledge, the proposed patch is not based on a code under GPL or another license that is incompatible with OpenCV- [x] The PR is proposed to the proper branch- [ ] There is a reference to the original bug report and related work- [ ] There is accuracy test, performance test and test data in opencv_extra repository, if applicable      Patch to opencv_extra has the same branch name.- [x] The feature is well documented and sample code can be built with the project CMake

pyrDown: offset HAL added, IPP removedopencv#25970Resolvesopencv#25976### Changes* HAL added for offset support so that border pixels can be fetched from outside of the image ROI (see `BORDER_ISOLATED` parameter)* IPP removed since there is `pyrUp` instead of `pyrDown` and there's no easy way to fix this other than rewriting it from scratch* replaced old C call by modern `cv::pyrDown`### Pull Request Readiness ChecklistSee details athttps://github.com/opencv/opencv/wiki/How_to_contribute#making-a-good-pull-request- [x] I agree to contribute to the project under Apache 2 License.- [x] To the best of my knowledge, the proposed patch is not based on a code under GPL or another license that is incompatible with OpenCV- [x] The PR is proposed to the proper branch- [ ] There is a reference to the original bug report and related work- [x] There is accuracy test, performance test and test data in opencv_extra repository, if applicable      Patch to opencv_extra has the same branch name.- [x] The feature is well documented and sample code can be built with the project CMake

…ffsetAdded offset for HAL as ofs2idx expects 1-based indexopencv#26080See details athttps://github.com/opencv/opencv/wiki/How_to_contribute#making-a-good-pull-request- [x] I agree to contribute to the project under Apache 2 License.- [x] To the best of my knowledge, the proposed patch is not based on a code under GPL or another license that is incompatible with OpenCV- [ ] The PR is proposed to the proper branch- [ ] There is a reference to the original bug report and related work- [ ] There is accuracy test, performance test and test data in opencv_extra repository, if applicable      Patch to opencv_extra has the same branch name.- [ ] The feature is well documented and sample code can be built with the project CMake

Added HAL interface for Lukas-Kanade optical flowopencv#26143### Pull Request Readiness ChecklistSee details athttps://github.com/opencv/opencv/wiki/How_to_contribute#making-a-good-pull-request- [x] I agree to contribute to the project under Apache 2 License.- [x] To the best of my knowledge, the proposed patch is not based on a code under GPL or another license that is incompatible with OpenCV- [ ] The PR is proposed to the proper branch- [ ] There is a reference to the original bug report and related work- [ ] There is accuracy test, performance test and test data in opencv_extra repository, if applicable      Patch to opencv_extra has the same branch name.- [ ] The feature is well documented and sample code can be built with the project CMake

HAL interface for Sharr derivatives needed for Lukas-Kanade algorithmopencv#26163### Pull Request Readiness ChecklistSee details athttps://github.com/opencv/opencv/wiki/How_to_contribute#making-a-good-pull-request- [x] I agree to contribute to the project under Apache 2 License.- [x] To the best of my knowledge, the proposed patch is not based on a code under GPL or another license that is incompatible with OpenCV- [ ] The PR is proposed to the proper branch- [ ] There is a reference to the original bug report and related work- [ ] There is accuracy test, performance test and test data in opencv_extra repository, if applicable      Patch to opencv_extra has the same branch name.- [ ] The feature is well documented and sample code can be built with the project CMake

Added Fastcv HAL changes in the 3rdparty folder.Includes HAL code , Fastcv libs and HeadersChange-Id: I2f0ddb1f57515c82ae86ba8c2a82965b1a9626ec

Reorganized the files in the folder,Added rules to download the fastcv binsfrom the 3rdparty repoChange-Id: Ia66f138894d3e8a06d0f32a6e7ce3359619189d7