Record the multi-platform build strategy as its own decision: cargo-zigbuild
for the four non-macOS targets, the static/standalone posture per platform,
the Windows synchronization stub, the test->build matrix workflow, and the
macOS deferral with its licensing rationale (the public CI image can't carry
the SDK). Shrinks the ci-001 amendment to a pointer; updates the index.
Runtime-verified by the user: Linux x86_64 + Windows aarch64 run correctly.
claude@clouddev1