Add channel edge handling to PinholeSPECTUB

[TommasoFerri97]

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Changes in this pull request

This pull request adds support for channel-edge pinhole collimators in PinholeSPECTUB, while preserving the existing knife-edge implementation.

The main changes are:

• Added a collimator type parameter to distinguish between knife-edge and channel-edge pinholes.
• Added the channel width (dycm) to the pinhole geometry definition.
• Extended the collimator parameter reader to load the additional channel-edge information.
• Added the geometrical treatment of finite channel width in the PinholeSPECTUB weight calculation.
• The original knife-edge calculation is retained when the collimator type is knife or when the channel width is set to zero.

Testing performed

The channel-edge implementation was tested with a PinholeSPECTUB reconstruction using a finite-width pinhole channel.

Checklist before requesting a review

• I have performed a self-review of my code
• The code builds and runs on my machine

Contribution Notes

Please tick the following:

• The content of this Pull Request (the Contribution) is intentionally submitted for inclusion in STIR (the Work) under the terms and conditions of the Apache-2.0 License.
• I (or my institution) have signed the STIR Contribution License Agreement (not required for small changes).

[codacy-production]

Up to standards ✅

🟢 Issues 0 issues

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🟢 Metrics 36 complexity · 46 duplication

Metric	Results
Complexity	36
Duplication	46

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