Add LSM program support and fix emit bugs

Add full LSM (Linux Security Module) attach pipeline to the loader:
BTF func ID resolution, BPF_LINK_CREATE-based attachment, section name
detection, and with-bpf-session macro support. Fix two emit.lisp bugs:
always emit mov r0,src on return (needed for multi-branch convergence)
and correct the parallel move safety check to test destination registers.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>