Phase 3 - Address space (DONE, both platforms verified)

orbistoun-mem. Implement the two platform primitives - mmap with MAP_FIXED_NOREPLACE on Unix, VirtualAlloc2 placeholders on Windows - behind the already-tested validation layer. Unix verified in the multipass VM per D027.

Delivered on Windows. orbistoun-cli load <file> --base <addr> reserves the span a module demands and reports the layout. Verified on a 96 KiB module and a 96 MB commercial executable; a request for an unavailable address is refused rather than silently relocated. See D054 - running it corrected the design from per-segment to per-span.

Linux verified in the multipass VM per D027 - and it was broken (D055). All four reservation tests failed there while Windows passed; two bugs, including error mapping that reported every mmap failure as a conflict. 8/8 on both platforms now.