Python: Add cell filter reference to perforation intervals

Lets a script attach a cell filter to a RimPerforationInterval as a
typed reference so subsequent work can gate completion-export
connections by the filter's cell mask. Pure metadata in this commit:
no consumer of RimPerforationInterval is modified, the field exists
purely as an API surface.

Add a non-scriptable caf::PdmPtrField<RimCellFilter*> m_cellFilter to
RimPerforationInterval with public cellFilter()/setCellFilter()
accessors and a "Cell Filter" group in the property panel between the
existing geometry/flow group and the Date Settings group. The field is
deliberately non-scriptable: a scriptable PdmPtrField round-trips in
Python as an opaque "ClassName:0xADDR" string rather than a resolved
object, defeating the point. Two CAF object methods on
RimcPerforationInterval expose the relationship:

- AddFilter (perf.add_filter(filter)) sets the pointer; replaces any
  existing filter (single filter per perforation).
- cell_filter (perf.cell_filter()) resolves to the referenced
  RimCellFilter object on read, mirroring the valve.template() pattern.

Composition stays in RimCombinedFilter: a script that wants AND/OR
across multiple filters attaches a combined filter as the single
filter on the perforation.

The Python example in PythonExamples builds a case-level AND combined
filter (PERMX 100..20000 AND K=5..10), creates a modeled well path
with two perforation intervals, and shares the same filter between
them. test_perforation_filter.py covers single-set, replace-on-second-
add, and shared-pointer round-trips.

ApplicationLibCode/ProjectDataModelCommands/RimcPerforationInterval.cpp

@@ -18,6 +18,7 @@
 
 #include "RimcPerforationInterval.h"
 
+#include "RimCellFilter.h"
 #include "RimEclipseCase.h"
 #include "RimPerforationCollection.h"
 #include "RimPerforationInterval.h"
@@ -80,3 +81,55 @@ QString RimcPerforationInterval_addValve::classKeywordReturnedType() const
 {
     return RimWellPathValve::classKeywordStatic();
 }
+
+CAF_PDM_OBJECT_METHOD_SOURCE_INIT( RimPerforationInterval, RimcPerforationInterval_addFilter, "AddFilter" );
+
+//--------------------------------------------------------------------------------------------------
+///
+//--------------------------------------------------------------------------------------------------
+RimcPerforationInterval_addFilter::RimcPerforationInterval_addFilter( caf::PdmObjectHandle* self )
+    : caf::PdmVoidObjectMethod( self )
+{
+    CAF_PDM_InitObject( "Add Cell Filter", "", "", "Set the cell filter associated with this perforation interval (replaces any existing filter)" );
+
+    CAF_PDM_InitScriptableFieldNoDefault( &m_filter, "Filter", "", "", "", "Cell Filter" );
+}
+
+//--------------------------------------------------------------------------------------------------
+///
+//--------------------------------------------------------------------------------------------------
+std::expected<caf::PdmObjectHandle*, QString> RimcPerforationInterval_addFilter::execute()
+{
+    auto* perfInterval = self<RimPerforationInterval>();
+    perfInterval->setCellFilter( m_filter() );
+    perfInterval->updateConnectedEditors();
+
+    return nullptr;
+}
+
+CAF_PDM_OBJECT_METHOD_SOURCE_INIT( RimPerforationInterval, RimcPerforationInterval_cellFilter, "cell_filter" );
+
+//--------------------------------------------------------------------------------------------------
+///
+//--------------------------------------------------------------------------------------------------
+RimcPerforationInterval_cellFilter::RimcPerforationInterval_cellFilter( caf::PdmObjectHandle* self )
+    : PdmObjectMethod( self, PdmObjectMethod::NullPointerType::NULL_IS_VALID, PdmObjectMethod::ResultType::PERSISTENT_TRUE )
+{
+    CAF_PDM_InitObject( "Cell Filter", "", "", "Cell filter associated with this perforation interval, or null if none" );
+}
+
+//--------------------------------------------------------------------------------------------------
+///
+//--------------------------------------------------------------------------------------------------
+std::expected<caf::PdmObjectHandle*, QString> RimcPerforationInterval_cellFilter::execute()
+{
+    return self<RimPerforationInterval>()->cellFilter();
+}
+
+//--------------------------------------------------------------------------------------------------
+///
+//--------------------------------------------------------------------------------------------------
+QString RimcPerforationInterval_cellFilter::classKeywordReturnedType() const
+{
+    return RimCellFilter::classKeywordStatic();
+}

ApplicationLibCode/ProjectDataModelCommands/RimcPerforationInterval.h

@@ -25,6 +25,7 @@
 
 #include <QString>
 
+class RimCellFilter;
 class RimValveTemplate;
 
 //==================================================================================================
@@ -46,3 +47,33 @@ private:
     caf::PdmField<double>               m_endMd;
     caf::PdmField<int>                  m_valveCount;
 };
+
+//==================================================================================================
+/// Set the cell filter associated with this perforation interval. Replaces any existing filter.
+//==================================================================================================
+class RimcPerforationInterval_addFilter : public caf::PdmVoidObjectMethod
+{
+    CAF_PDM_HEADER_INIT;
+
+public:
+    RimcPerforationInterval_addFilter( caf::PdmObjectHandle* self );
+
+    std::expected<caf::PdmObjectHandle*, QString> execute() override;
+
+private:
+    caf::PdmPtrField<RimCellFilter*> m_filter;
+};
+
+//==================================================================================================
+/// Returns the cell filter associated with this perforation interval, or null if none.
+//==================================================================================================
+class RimcPerforationInterval_cellFilter : public caf::PdmObjectMethod
+{
+    CAF_PDM_HEADER_INIT;
+
+public:
+    RimcPerforationInterval_cellFilter( caf::PdmObjectHandle* self );
+
+    std::expected<caf::PdmObjectHandle*, QString> execute() override;
+    QString                                       classKeywordReturnedType() const override;
+};