pyrDown: offset HAL added, IPP removed opencv#25970

Resolves opencv#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`

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Fixed asserts in fillPoly

Add support for QNX opencv#25832

Build and test instruction for QNX:
https://github.com/chachoi-world/qnx-ports/blob/main/opencv/README.md

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…-26000

got rid of std prefix

Improved samples/python/tracker.py docstring opencv#25959

This PR removed unused arguments and updated existing argument placeholders to be more descriptive of what they are.

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…python-tutorials

Remove empty Additional Resources and Exercises fields from tutorials opencv#26002

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This PR is in response to issue [26001](opencv#26001)

This pull request addresses the issue of empty "Additional Resources" and "Exercises" fields in several OpenCV-Python tutorials. The empty sections have been removed to improve the clarity and consistency of the documentation.

imgproc: add specific error code when cvtColor is used on an image with an invalid number of channels opencv#25981

close opencv#25971

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doc: remove duplicated OpenCV Theory at ToC in Basic Drawing opencv#26018

Close opencv#26017

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correct "enviroment" to "environment"

…crash

Fix typos opencv#26038

Fix typos

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…her-py-markdown

fixing issue 25962

Docfix - Remove notice on using deprecated itemset

Fix: reduce redundant code by optimizing device name retrieval

…et_votes

speedup random forest getVotes method.

Free Variant variable after usage in DShow back-end

…cation

Einsum buffer allocation fix opencv#26059

This PR fixed buffer allocation issue in Einsum layer that causes segmentation fault on 32bit platforms. Related issue opencv#26008 

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Fixed the simd bugs of iPow8u and iPow16u opencv#26061

Add the following cases in opencv_perf_core:

* OCL_PowFixture_iPow.iPow/0, where GetParam() = (640x480, 8UC1)
* OCL_PowFixture_iPow.iPow/2, where GetParam() = (640x480, 16UC1)

iPow8u and iPow16u failed to call to simd accelerating while executing.

Fix the bug by changing the input type of iPow_SIMD function.

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…ert on Intel iGPU.

Enable `CV_SIMD_SCALABLE` for median blur.

Removed duplicated code in Pow implementation that triggers wrong assert on Intel iGPU

build/doc: disabled libdc1394 by default, documented framebuffer options

…e-tests

DNN(ONNX): Enabled several OpenCL conformance tests opencv#26053

The tests also work in 5.x

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