ENH: Add RadReirradiation extension (#2330)

* Add RadComp extension

Hello Slicer Team!

I am submitting **RadComp**, a new Python scripted module designed for Radiotherapy clinical Re-irradiation analysis. 

**Key Features:**
* Image registration and alignment of previous and current radiotherapy plans.
* Automatic EQD2 biological dose calculation.
* Native and interactive DVH metrics integrated directly into the Slicer GUI.
* Memory-optimized workflow for recalculations with different alpha/beta ratios.
* Easy structure visibility toggling for cleaner dosimetric analysis.

Repository: https://github.com/LuisParedesOcampo/SlicerRadComp
Web: https://radcomp.streamlit.app

Thank you for reviewing!

* Remove status field from RadComp.s4ext

Removed the status field from the RadComp.s4ext file.

* Delete RadComp.s4ext

* Migrate metadata to JSON format

Replaced the deprecated .s4ext file with the new RadComp.json format to pass repository structure validation. Also updated SlicerRT to be a user workflow dependency rather than a build dependency.

* Remove SlicerRT dependency from RadComp.json

* Rename RadComp.json to SlicerRadComp.json

* Rename SlicerRadComp.json to RadComp.json

* Change tier value from 3 to 1 in RadComp.json

* Update RadComp.json

* Update scm_url in RadComp.json

* Add RadReirradiation.json file

* Update RadReirradiation.json

* Update RadReirradiation.json

Author: LuisParedesOcampo

RadReirradiation.json

@@ -0,0 +1,8 @@
+{
+  "$schema": "https://raw.githubusercontent.com/Slicer/Slicer/main/Schemas/slicer-extension-catalog-entry-schema-v1.0.1.json#",
+  "build_subdirectory": ".",
+  "category": "Radiotherapy",
+  "scm_revision": "main",
+  "scm_url": "https://github.com/LuisParedesOcampo/SlicerRadReirradiation",
+  "tier": 1
+}