fix(codegen): Initialize UPROPERTY fields in generated Unreal C++ code

[brougkr]

Summary

UE5 strict mode requires all UPROPERTY fields to be explicitly initialized, otherwise the engine logs "property not initialized properly" errors at startup. This PR ensures generated Unreal C++ code properly initializes all UPROPERTY fields.

Changes

• Modified cpp_ty_init_fmt_impl to accept module parameter for enum type resolution
• Added initialization for enum types (PlainEnum) using the first variant as default value
• Updated all call sites in reducer/procedure/struct generation to pass the module

Before

UPROPERTY(BlueprintReadWrite, Category="SpacetimeDB")
EMyEnumType SomeEnumField;  // ERROR: property not initialized properly

After

UPROPERTY(BlueprintReadWrite, Category="SpacetimeDB")
EMyEnumType SomeEnumField = EMyEnumType::FirstVariant;  // OK

Affected generated code

• Reducer args structs (FXxxReducerArgs)
• Reducer classes (UXxxReducer)
• Procedure args structs (FXxxProcedureArgs)
• Product type structs (FXxxType)

Test plan

• Build codegen crate successfully
• Generate bindings for a project with enum types
• Verify generated code has proper initializers
• Build Unreal project without "property not initialized properly" errors

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Generated with Claude Code