Add M1 macro property parsing

[sabino]

Summary

• parse macro property YAML entries for project macros under parsed model and macro paths
• emit dbt-shaped macro description, patch_path, and arguments fields with argument order and null type defaults
• warn on unmatched macro patches and fail duplicate macro property patches
• update M1 plan status and add focused fixtures

Validation

• dbt Core 1.10.15 oracle for macro property description, patch_path, arguments, and duplicate patch failure behavior
• zig fmt --check src/project.zig src/root.zig
• zig build --cache-dir /tmp/dxt-zig-cache-local --global-cache-dir /tmp/dxt-zig-cache-global
• zig build test --cache-dir /tmp/dxt-zig-cache-local --global-cache-dir /tmp/dxt-zig-cache-global
• zig build -Doptimize=ReleaseSafe --cache-dir /tmp/dxt-zig-cache-local --global-cache-dir /tmp/dxt-zig-cache-global
• pytest -q
• python scripts/check_public_safety.py
• python scripts/check_runtime_boundary.py
• git diff --check

Agentic review: macro-property oracle subagent verified dbt Core 1.10.15 manifest field shape and gotchas. A later implementation reviewer did not return before shutdown, so local oracle plus gates are the review basis for this slice.