docs: audit & update all documentation to reflect current implementation

docs: audit & update all documentation to reflect current implementation

- POSIX_ROADMAP: 75→90 features (15 new: gettimeofday, mprotect, getrlimit/setrlimit, uname, getrusage, socket ops, LZ4, EPOLLET, lazy PLT, MIPS, SysV init, 50+ utilities, host test harness, native toolchain, mount syscall)
- README: 80→102 smoke tests, 47→115 host tests, 75→90 features, 52 userland programs listed
- BUILD_GUIDE: fixed init path (/sbin/fulltest), expanded utility list, updated test counts
- TESTING_PLAN: 80→102 smoke, 19→115 host tests
- SUPPLEMENTARY_ANALYSIS: LZ4 ❌→✅, per-CPU runqueues ❌→✅, test counts aligned
- AUDIT_REPORT: 3 additional fixes marked (sc_* macros, SMAP, schedule race)
- FULL_POSIX_AUDIT: 7/12 syscalls now ✅, Newlib/GCC/Binutils ports ✅ COMPLETE, kernel ~85%→~98% POSIX