ifcparse: store integer attribute values as int64_t to allow out-of-range timestamps

Setting an IfcInteger/IfcTimeStamp typed attribute (e.g. IfcOwnerHistory.CreationDate)
outside the signed 32-bit range corrupted the value instead of raising, since the
Python wrapper's set_attribute_value_py() truncated it with a plain static_cast<int>
before handing it to the C++ storage. Unix timestamps before 1901-12-13 or after
2038-01-19 silently wrapped around (e.g. 3000000000 became -1294967296) rather than
being rejected or stored correctly. Fixes #3058, equivalent to PR #8683 but ported to
this branch's rewritten ifcparse (snake_case files, variant_array/instance_data
storage, SWIG PyObject-based attribute setter) instead of the old IfcEntityInstanceData
sources, which no longer exist here.

The scalar slot of the attribute variant (Argument_INT) becomes int64_t. Integer
aggregates (Argument_AGGREGATE_OF_INT, e.g. CoordIndex) and instance/reference
identifiers stay 32-bit, since neither is the value that overflows here; this narrow
scope is kept on its own technical merits (aggregates and identifiers were never the
source of the bug, and widening them would be a much larger, riskier change for no
benefit) even though aothms said compatibility isn't a concern on this v0.9-track
branch. express::Base::set_attribute_value promotes the schema-generated int to
int64_t at a single choke point, so the generated setters keep compiling unchanged.
The STEP lexer, writer, and SWIG wrapper (set_attribute_value_py, pythonize) are all
widened together, since widening only the Python-facing setter would have silently
wrapped the value on file write instead of raising.

Verified in a build (IFC2X3 and IFC4, BUILD_IFCGEOM off, no kernels): pre-1901,
post-2038, both 32-bit boundaries, and a 9e12 value all round trip exactly both in
memory and through STEP text serialization (write then reopen). A value outside the
64-bit range now raises a clean exception instead of corrupting data. Ordinary
in-range integers and integer aggregates (e.g. IfcTriangulatedFaceSet.CoordIndex) are
unaffected. The existing util/test_attribute.py and test_file.py suites pass
unchanged; test_entity_instance.py has 5 pre-existing failures unrelated to this
change (confirmed identical on an unfixed build of this branch, caused by a missing
get_info_2 binding and _patch_swig_comparisons never being implemented here).

Generated with the assistance of an AI coding tool.

src/ifcparse/storage.h

@@ -161,18 +161,18 @@ namespace ifcopenshell {
 
         union {
             char value_char;     //types: OPERATOR
-            int value_int;       //types: INT, IDENTIFIER
+            int64_t value_int;   //types: INT, IDENTIFIER
             double value_double; //types: FLOAT
             const std::string* value_string;  //types: STR, ENUM, KEYWORD; lifetime managed by spf_lexer::string_pool_
         };
 
         token() : start_pos(0),
                   type(Token_NONE) {}
-        
+
         token(size_t start_position, token_type token_kind, const std::string& string_value)
             : start_pos(start_position), type(token_kind), value_string(&string_value) {}
 
-        token(size_t start_position, token_type token_kind, int integer_value)
+        token(size_t start_position, token_type token_kind, int64_t integer_value)
             : start_pos(start_position), type(token_kind), value_int(integer_value) {}
 
         token(size_t start_position, double floating_value)
@@ -196,7 +196,7 @@ namespace ifcopenshell {
         bool is_float();
         bool is_binary();
 
-        int as_int();
+        int64_t as_int();
         unsigned as_identifier();
         bool as_bool();
         boost::logic::tribool as_logical();