wasm-port-rebase: KiCad 10.0.4 rebase + WASM build adaptations

Root-side changes for the wasm-port-rebase work:
- kicad submodule bumped to wasm-port-rebase (43-commit rebase onto KiCad 10.0.4
  + the KiCad-10 WASM source adaptations)
- wasm/kiplatform/policy.cpp: GetPolicyEnumUInt -> std::optional (KiCad 10 API)
- wasm/stubs/api_plugin_stub.cpp: API_PLUGIN_MANAGER signature sync (KiCad 10 API)

Compiles 100% for pcbnew (3D viewer on, -O1); WASM link + e2e parity still pending.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

wasm/kiplatform/policy.cpp

@@ -5,6 +5,7 @@
 
 #include <kiplatform/policy.h>
 #include <wx/string.h>
+#include <optional>
 
 namespace KIPLATFORM
 {
@@ -17,10 +18,10 @@ PBOOL GetPolicyBool( const wxString& aKey )
     return PBOOL::NOT_CONFIGURED;
 }
 
-std::uint32_t GetPolicyEnumUInt( const wxString& aKey )
+std::optional<std::uint32_t> GetPolicyEnumUInt( const wxString& aKey )
 {
     // No enterprise policies in browser environment
-    return 0;
+    return std::nullopt;
 }
 
 } // namespace POLICY