formula: capstone-engine/capstone

[MeteorsLiu]

Summary

• Add the capstone-engine/capstone LLAR Formula from the Conan Center snapshot d034b32b3106d282c32f0a23314b5c6ba1b0fa69 and the pinned upstream 5.0.1 source.
• Cover the verified upstream CMake contract boundaries at 4.0.2, 5.0, 5.0.9, and 6.0.0-Alpha1 with the module-local tag comparator.
• Preserve shared, fPIC, and use_default_alloc options, install a relocatable capstone.pc, and validate the Conan consumer through pkg-config onTest.

Validation

• Exact 5.0.1 fresh build and independent consumer: darwin/arm64, passed.
• Exact 5.0.1 cache-hit consumer rerun: passed.
• Retained option matrix 5.0.1 with shared=ON, fPIC=OFF, use_default_alloc=OFF: passed.
• Threshold/range checks: 4.0.2, 5.0.8, 5.0.9, and 6.0.0-Alpha10 on darwin/arm64: passed.
• Default selection resolved to 6.0.0-Alpha10 and passed.
• 4.0.1 rejected below the earliest supported threshold.
• Staged and committed diff is limited to capstone-engine/capstone/**.

Closes #245