Merge pull request #26958 from amane-ame:pyramids_hal_rvv

Add RISC-V HAL implementation for cv::pyrDown and cv::pyrUp #26958

This patch implements `cv_hal_pyrdown/cv_hal_pyrup` function in RVV_HAL using native intrinsics, optimizing the performance for `cv::pyrDown`, `cv::pyrUp` and `cv::buildPyramids` with data types `{8U,16S,32F} x {C1,C2,C3,C4,Cn}`.

Tested on MUSE-PI (Spacemit X60) for both gcc 14.2 and clang 20.0.

```
$ ./opencv_test_imgproc --gtest_filter="*pyr*:*Pyr*"
$ ./opencv_perf_imgproc --gtest_filter="*pyr*:*Pyr*" --perf_min_samples=300 --perf_force_samples=300
```

<img width="1112" alt="Untitled" src="https://github.com/user-attachments/assets/235a9fba-0d29-434e-8a10-498212bac657" />


### Pull Request Readiness Checklist

See details at https://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

modules/imgproc/src/hal_replacement.hpp

@@ -1274,6 +1274,26 @@ inline int hal_ni_pyrdown_offset(const uchar* src_data, size_t src_step, int src
 #define cv_hal_pyrdown_offset hal_ni_pyrdown_offset
 //! @endcond
 
+/**
+   @brief Perform Gaussian Blur and upsampling for input tile.
+   @param depth Depths of source and destination image
+   @param src_data Source image data
+   @param src_step Source image step
+   @param dst_data Destination image data
+   @param dst_step Destination image step
+   @param src_width Source image width
+   @param src_height Source image height
+   @param dst_width Destination image width
+   @param dst_height Destination image height
+   @param cn Number of channels
+   @param border_type Border type
+*/
+inline int hal_ni_pyrup(const uchar* src_data, size_t src_step, int src_width, int src_height, uchar* dst_data, size_t dst_step, int dst_width, int dst_height, int depth, int cn, int border_type) { return CV_HAL_ERROR_NOT_IMPLEMENTED; }
+
+//! @cond IGNORED
+#define cv_hal_pyrup hal_ni_pyrup
+//! @endcond
+
 /**
    @brief Canny edge detector
    @param src_data Source image data

modules/imgproc/src/pyramids.cpp

@@ -1388,6 +1388,8 @@ void cv::pyrUp( InputArray _src, OutputArray _dst, const Size& _dsz, int borderT
     Mat dst = _dst.getMat();
     int depth = src.depth();
 
+    CALL_HAL(pyrUp, cv_hal_pyrup, src.data, src.step, src.cols, src.rows, dst.data, dst.step, dst.cols, dst.rows, depth, src.channels(), borderType);
+
 #ifdef HAVE_IPP
     bool isolated = (borderType & BORDER_ISOLATED) != 0;
     int borderTypeNI = borderType & ~BORDER_ISOLATED;