Kernel hardening (proc.rs +23 lines):
- NGROUPS_MAX=65536 enforcement in Groups write handler
- Reject non-u32-aligned writes with EINVAL
- Process-scope propagation: setgroups() now fans out to
ALL threads sharing the same owner_proc_id
Relibc robustness:
- setrlimit: EINVAL for unknown resources (was silent Ok)
- posix_getgroups: kernel readback when cache is empty,
fixes exec() cache-staleness gap
Oracle audit fixes: H (kernel cap), E (alignment reject),
G (process-scope), C (cache readback), B (rlimit errors)