reject non-integer JSON numbers where an integer is expected

[aysha-afrah26]

nlohmann's get<T>() for an integral T converts a JSON float with a bare static_cast, so a value outside the range of T is undefined behavior (UBSan float-cast-overflow), a fraction is truncated and an out-of-range integer wraps. Several readers apply it to external JSON: JsonExporter::fromJson picks std::vector<int> from the first array element only and then casts every element (ImportBlackboardFromJSON with {"v":[1, 1e300]}), a json:[1e300] value on a std::vector<int> port in the XML, async_delay in loadSubstitutionRuleFromJSON, and the uid/position/mode fields of the Groot2 HOOK_INSERT, BREAKPOINT_UNLOCK and HOOK_REMOVE requests. On the Groot2 server a uid of node_uid + 65536 or node_uid + 0.5 silently installs the hook on that real node, and 1e300 is UB on the server thread. UBSan reports 1e+300 is outside the range of representable values of type 'int' (json.hpp:4983) for the first three, and on master the hook request with a wrapped uid is accepted. #1186 fixed the scalar branch of fromJson; this covers the array branch and every other get<integral> call on external input in the tree (the BT_JSON_CONVERTER fields belong to user types and are left alone). The new inline JsonToInteger<T> in json_export.h accepts only JSON integers representable as T and throws RuntimeError otherwise, so a bad value takes the existing error paths; the Groot2 server already turns the exception into an error reply.

Behavior change: an integer array with a real or out-of-range element, and a fractional or out-of-range async_delay or hook uid, now throw instead of being converted. Inline header additions only, no ABI change. The new tests JsonTest.IntegerValuesAreRangeChecked, Substitution.ParserRejectsNonIntegerAsyncDelay and Groot2PublisherIntegration.HookRequestRejectsNonIntegerUid fail on master and pass with the change. Full ctest is 549/549 under ASan+UBSan on macOS, and clang-format and codespell are clean (clang-tidy-21 was not available locally).