[zhangzhenghao]

Summary

• Rebased onto main (087781a).
• Use GoogleTest for allocation failure coverage in tests/clap-test.cpp (renamed from c-api-allocation-test.cpp).
• Combine resampling and audio decoding coverage in tests/audio-test.cpp using GoogleTest, preserving all original input cases, rate combinations and numerical thresholds.
• Remove the intermediate audio-decode-test.cpp and obsolete standalone resampling target/CTest registration; clap_audio runs both suites (14 GoogleTest cases).
• Keep all unrelated tests unchanged.
• Build pinned GoogleTest v1.17.0 from its source submodule only with BUILD_TESTING enabled.

Verification

• Full Release static build: all 31 default CTests passed.
• Full Release shared build: all 30 default CTests passed (allocation test remains static-only).
• All 14 combined audio GoogleTest cases passed; XML report verified.
• Fixture-free GoogleTest discovery passed; missing fixture argument correctly rejected.
• Deliberately invalid audio fixture correctly failed through GoogleTest with nonzero exit status.
• Unrelated tests verified byte-identical to the previous PR head.
• clang-format 18.1.8 and git diff --check passed.
• Windows x64 and ARM64 full CI passed on f7a9871, including the audio CTest; ARM64 passed after rerunning a transient GitHub FFmpeg download failure. Shared GoogleTest now has both its import definition and its runtime DLL deployed beside the Windows test executable.