Fix integer overflow crash in PADS ASCII importer

The scaleSize(), scaleCoord(), and partCoordScaler functions cast 64-bit
nanometer values to int without bounds checking. For MILS-unit files with
large coordinates (e.g. 124,020 mils * 25,400 nm/mil = 3.15 billion nm),
this exceeds INT_MAX and triggers undefined behavior, crashing in debug
builds via KiROUND's overflow assertion and silently wrapping in release.

Clamp all three conversion sites to [INT_MIN, INT_MAX] before casting.

Also fix two pre-existing build errors from recent header optimization
commits (missing netclass.h and component_class_manager.h includes).

Fixes https://gitlab.com/kicad/code/kicad/-/issues/23054

pcbnew/component_classes/component_class_cache_proxy.h

@@ -22,6 +22,7 @@
 #define PCBNEW_COMPONENT_CLASS_CACHE_PROXY_H
 
 #include <component_classes/component_class.h>
+#include <component_classes/component_class_manager.h>
 #include <footprint.h>
 
 /*

pcbnew/edit_track_width.cpp

@@ -23,6 +23,7 @@
  */
 
 #include <board_design_settings.h>
+#include <netclass.h>
 #include <pcb_edit_frame.h>
 #include <pcbnew_id.h>
 #include <pcb_track.h>

pcbnew/pcb_io/pads/pcb_io_pads.cpp

@@ -25,6 +25,7 @@
 #include "pads_layer_mapper.h"
 
 #include <algorithm>
+#include <climits>
 #include <cmath>
 #include <fstream>
 #include <functional>
@@ -357,9 +358,10 @@ void PCB_IO_PADS::loadFootprints()
 
             long long res_nm = val_nm - origin_nm;
 
-            if( !is_x ) res_nm = -res_nm;
+            if( !is_x )
+                res_nm = -res_nm;
 
-            return static_cast<int>( res_nm );
+            return static_cast<int>( std::clamp<long long>( res_nm, INT_MIN, INT_MAX ) );
         };
 
         footprint->SetPosition( VECTOR2I( partCoordScaler( pads_part.location.x, true ),
@@ -2158,7 +2160,8 @@ std::map<wxString, PCB_LAYER_ID> PCB_IO_PADS::DefaultLayerMappingCallback(
 
 int PCB_IO_PADS::scaleSize( double aVal ) const
 {
-    return static_cast<int>( m_unitConverter.ToNanometersSize( aVal ) );
+    int64_t nm = m_unitConverter.ToNanometersSize( aVal );
+    return static_cast<int>( std::clamp<int64_t>( nm, INT_MIN, INT_MAX ) );
 }
 
 
@@ -2169,10 +2172,8 @@ int PCB_IO_PADS::scaleCoord( double aVal, bool aIsX ) const
     long long origin_nm = static_cast<long long>( std::round( origin * m_scaleFactor ) );
     long long val_nm = static_cast<long long>( std::round( aVal * m_scaleFactor ) );
 
-    if( aIsX )
-        return static_cast<int>( val_nm - origin_nm );
-    else
-        return static_cast<int>( origin_nm - val_nm );
+    long long result = aIsX ? ( val_nm - origin_nm ) : ( origin_nm - val_nm );
+    return static_cast<int>( std::clamp<long long>( result, INT_MIN, INT_MAX ) );
 }