Crash on invalid UTF-8 bytes in Natspec

## Description

```
./solc/solc --optimize --ir minimized-from-ab4ee1498fff0c71961d81fc308f1dee0be16f33
Uncaught exception:
Dynamic exception type: nlohmann::json_abi_v3_12_0::detail::type_error
std::exception::what: [json.exception.type_error.316] invalid UTF-8 byte at index 0: 0xF7
```

Input:
```
$ xxd minimized-from-ab4ee1498fff0c71961d81fc308f1dee0be16f33
00000000: 2f2f 2ff7 0a63 6f6e 7472 6163 7420 677b ///..contract g{
00000010: 7d }
```

GDB backtrace:
```
(gdb) r
Starting program: /home/matesoos/development/solidity/develop/build/solc/solc --optimize --ir minimized-from-ab4ee1498fff0c71961d81fc308f1dee0be16f33
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/usr/lib/libthread_db.so.1".

Catchpoint 1 (exception thrown), 0x00007ffff7cb213a in __cxxabiv1::__cxa_throw (obj=0x55555649b860, tinfo=0x55555643f578 ,
dest=0x555555791a30 ) at /usr/src/debug/gcc/gcc/libstdc++-v3/libsupc++/eh_throw.cc:81
81 PROBE2 (throw, obj, tinfo);
(gdb) bt
#0 0x00007ffff7cb213a in __cxxabiv1::__cxa_throw (obj=0x55555649b860, tinfo=0x55555643f578 ,
dest=0x555555791a30 ) at /usr/src/debug/gcc/gcc/libstdc++-v3/libsupc++/eh_throw.cc:81
#1 0x000055555613ca04 in nlohmann::json_abi_v3_12_0::detail::serializer, std::allocator >, bool, long, unsigned long, double, std::allocator, nlohmann::json_abi_v3_12_0::adl_serializer, std::vector >, void> >::dump_escaped (this=this@entry=0x7fffffffb270, s=, ensure_ascii=)
at /home/matesoos/development/solidity/develop/deps/nlohmann-json/include/nlohmann/detail/output/serializer.hpp:513
#2 0x000055555613fd6c in nlohmann::json_abi_v3_12_0::detail::serializer, std::allocator >, bool, long, unsigned long, double, std::allocator, nlohmann::json_abi_v3_12_0::adl_serializer, std::vector >, void> >::dump (this=this@entry=0x7fffffffb270, val=..., pretty_print=pretty_print@entry=false, ensure_ascii=ensure_ascii@entry=true, indent_step=indent_step@entry=0,
current_indent=current_indent@entry=0) at /home/matesoos/development/solidity/develop/deps/nlohmann-json/include/nlohmann/detail/output/serializer.hpp:250
#3 0x0000555556140230 in nlohmann::json_abi_v3_12_0::detail::serializer, std::allocator >, bool, long, unsigned long, double, std::allocator, nlohmann::json_abi_v3_12_0::adl_serializer, std::vector >, void> >::dump (this=this@entry=0x7fffffffb270, val=..., pretty_print=pretty_print@entry=false, ensure_ascii=ensure_ascii@entry=true, indent_step=,
current_indent=current_indent@entry=0) at /home/matesoos/development/solidity/develop/deps/nlohmann-json/include/nlohmann/detail/output/serializer.hpp:170
#4 0x000055555614033d in nlohmann::json_abi_v3_12_0::detail::serializer, std::allocator >, bool, long, unsigned long, double, std::allocator, nlohmann::json_abi_v3_12_0::adl_serializer, std::vector >, void> >::dump (this=this@entry=0x7fffffffb270, val=..., pretty_print=pretty_print@entry=false, ensure_ascii=ensure_ascii@entry=true, indent_step=indent_step@entry=0,
current_indent=current_indent@entry=0) at /home/matesoos/development/solidity/develop/deps/nlohmann-json/include/nlohmann/detail/output/serializer.hpp:180
#5 0x0000555556140230 in nlohmann::json_abi_v3_12_0::detail::serializer, std::allocator >, bool, long, unsigned long, double, std::allocator, nlohmann::json_abi_v3_12_0::adl_serializer, std::vector >, void> >::dump (this=0x7fffffffb270, val=..., pretty_print=pretty_print@entry=false, ensure_ascii=, indent_step=indent_step@entry=0, current_indent=0)
at /home/matesoos/development/solidity/develop/deps/nlohmann-json/include/nlohmann/detail/output/serializer.hpp:170
#6 0x0000555556140b41 in nlohmann::json_abi_v3_12_0::basic_json, std::allocator >, bool, long, unsigned long, double, std::allocator, nlohmann::json_abi_v3_12_0::adl_serializer, std::vector >, void>::dump (this=this@entry=0x7fffffffb620,
indent=indent@entry=-1, indent_char=indent_char@entry=32 ' ', ensure_ascii=ensure_ascii@entry=true,
error_handler=error_handler@entry=nlohmann::json_abi_v3_12_0::detail::error_handler_t::strict)
at /home/matesoos/development/solidity/develop/deps/nlohmann-json/include/nlohmann/json.hpp:1313
#7 0x0000555556138441 in solidity::util::jsonPrint (_input=..., _format=...) at /home/matesoos/development/solidity/develop/libsolutil/JSON.cpp:132
#8 solidity::util::jsonCompactPrint (_input=...) at /home/matesoos/development/solidity/develop/libsolutil/JSON.cpp:127
#9 0x0000555555873a72 in solidity::frontend::CompilerStack::createMetadata[abi:cxx11](solidity::frontend::CompilerStack::Contract const&, bool) const (this=this@entry=0x55555649a6c0,
_contract=..., _forIR=_forIR@entry=true) at /home/matesoos/development/solidity/develop/libsolidity/interface/CompilerStack.cpp:1863
#10 0x0000555555874bcc in solidity::frontend::CompilerStack::createCBORMetadata (this=this@entry=0x55555649a6c0, _contract=..., _forIR=_forIR@entry=true)
at /home/matesoos/development/solidity/develop/libsolidity/interface/CompilerStack.cpp:1962
#11 0x00005555558774d3 in solidity::frontend::CompilerStack::generateIR (this=this@entry=0x55555649a6c0, _contract=..., _unoptimizedOnly=)
at /home/matesoos/development/solidity/develop/libsolidity/interface/CompilerStack.cpp:1651
#12 0x000055555587d1e1 in solidity::frontend::CompilerStack::compile (this=0x55555649a6c0, _stopAfter=)
at /home/matesoos/development/solidity/develop/libsolidity/interface/CompilerStack.cpp:806
#13 0x0000555555762a31 in solidity::frontend::CommandLineInterface::compile (this=this@entry=0x7fffffffc7b0) at /usr/include/c++/15.2.1/bits/unique_ptr.h:192
#14 0x000055555576f320 in solidity::frontend::CommandLineInterface::processInput (this=0x7fffffffc7b0) at /home/matesoos/development/solidity/develop/solc/CommandLineInterface.cpp:859
#15 0x000055555576f720 in solidity::frontend::CommandLineInterface::run (this=this@entry=0x7fffffffc7b0, _argc=_argc@entry=4, _argv=_argv@entry=0x7fffffffccd8)
at /home/matesoos/development/solidity/develop/solc/CommandLineInterface.cpp:766
#16 0x0000555555725341 in main (argc=4, argv=0x7fffffffccd8) at /home/matesoos/development/solidity/develop/solc/main.cpp:40
```

## Environment

- Compiler version: latest `develop`, i.e. 63131344df6e0038729fa9da4f04c1e88a2ab087
- Compilation pipeline (legacy, IR, EOF): default `--optimize --ir `
- Target EVM version (as per compiler settings): default latest
- Framework/IDE (e.g. Foundry, Hardhat, Remix): N/A
- EVM execution environment / backend / blockchain client: N/A
- Operating system: Linux

## Steps to Reproduce

Run as above.

Start by running the reported solc command with the minimized input containing the invalid 0xF7 byte. Read libsolutil/JSON.cpp around jsonPrint and libsolidity/interface/CompilerStack.cpp around createMetadata and createCBORMetadata, following the supplied backtrace. Done means this input no longer terminates with the nlohmann::json invalid-UTF-8 exception.

Written by the indexing model from the issue text.