Add regression coverage for native VM module alias order

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Risky behavior now covered

• Native VM module loading now has deterministic coverage for the logical alias/probe order used by loadNative, including legacy qagame -> game, project-native game/server, cgame/client, and ui/frontend aliases.
• The test also covers non-generic modules staying on the legacy platform-specific fallback path and capacity-limited alias construction.

Test files added/updated

• Updated tests/unit/test_vm_native_module.c with alias/probe-order assertions.
• Updated src/qcommon/vm_native_module.c/.h to expose the alias ordering helper used by production loading.
• Updated CMakeLists.txt so unit_vm_native_module links the shared string helper implementation needed by case-insensitive alias checks.

Why this reduces regression risk

• Recent native-module compatibility work affects core mod/full-conversion loading. A small ordering regression could break expected native artifact names even when the files exist.
• The tested helper is now the same path consumed by loadNative, so future alias or ordering changes will fail in a focused unit test before reaching runtime.

Validation

• cmake -S . -B build-coverage-tests -DBUILD_TESTING=ON -DBUILD_UNIT_TESTS=ON
• cmake --build build-coverage-tests --target unit_vm_native_module
• ctest --test-dir build-coverage-tests -R unit_vm_native_module --output-on-failure