feat: S4 kernel eventfd wired — all 4 phases shipped and boot verified
S1: sem_open refcounting ✅
S2: name canonicalization (sem.* prefix) + va_list parsing ✅
S3: EINTR handling (Semaphore::wait c_int errno, retry loop) ✅
S4: kernel eventfd (event.rs eventfd field + scheme/event.rs path parsing) ✅
Kernel P0-eventfd-kernel.patch wired into recipe, compiles, boots.
Greeter ready on VT 3 verified.
Docs: RELIBC-AGAINST-GLIBC-ASSESSMENT.md (glibc 2.41 cross-reference) ✅
All 4 phases implemented, shipped, boot verified.
vasilito
cfe9d70e47