Implements per-user/project namespace isolation with memory caps, LRU eviction, and session cleanup. Prevents glibc select() crashes when file descriptors exceed 1024 (FD_SETSIZE), a problem that still affects many modern tools.
Solves #63 (memory leak), #176 (too many open files), #431 (session growth), #5 (zombie processes).
Solves #63 (memory leak), #176 (too many open files), #431 (session growth), #5 (zombie processes).