Add recursive final-bundle Mach-O audit - #343

The installed macOS packager only checked its known executable and WebGPU library, so native extensions or other Mach-O files could enter the final bundle with the wrong architecture, deployment target, install name, rpath, or unresolved dependency.

This adds a product-neutral installed SDK verifier that recursively inventories the final bundle without following symlinks, audits every architecture slice and dependency path, rejects unsafe paths and concurrent mutation, and emits bounded deterministic JSON evidence before the outer bundle signature. The versioned schema and tools-only install profile make the verifier reusable by external packagers.

Validation:

• 15 portable adversarial contracts, including native extensions, fat/wrong architecture, malformed load commands, Unicode/case collisions, escaping/dangling/absolute/internal symlinks, special entries, mutation, and exact 10,000-entry time/FD/RSS/evidence bounds
• real installed-SDK macOS consumer compiles a host, dylib, and .node bundle, completes 10 deterministic audits in about 1.6 seconds with 2,510-byte evidence, and rejects a mutated dangling dependency
• dedicated Linux, Windows, and self-hosted macOS workflow

Closes #328