docs: the communication stack — /protocol namespace, layered model, non-unix hierarchy, SMEP/SMAP plan

The security-track design set. communication.md is the model: four layers
(namespace / protocol / channel / transport), packets and signals, parties
addressed by the channel and objects by target, transports as replaceable
buffer+doorbell mechanisms. protocol-namespace.md is L3+L2: /protocol names
contracts, resolution establishes a channel, init is the registrar,
restriction is per-process namespace delegation (with the microphone-prompt
worked example), the envelope is the universal packet header, migration
P1-P5 retires ServiceId. file-system-hierarchy.md replaces the unix-FHS
spec with the danos-native tree (/applications, /protocol, /system,
/volumes) and its migration table. ipc.md is re-cut as the kernel-ipc
transport document. smep-smap.md designs the kernel hardening: copy
discipline for the eight raw user-pointer syscalls, then SMEP, then SMAP
as a permanent tripwire.

docs/python-on-danos-milestones.md

@@ -82,7 +82,7 @@ return real answers.
 - `--disable-shared`; static `Modules/Setup`: `posix errno _io _codecs _weakref
   time math _stat _collections itertools _functools _locale _sre` plus what the
   interpreter core insists on; threadless build (WASI precedent).
-- `Lib/` on the FAT image under the FSH (e.g. `/system/python/lib`);
+- `Lib/` on the FAT image under the hierarchy (e.g. `/system/python/lib`);
   `PYTHONHOME` set accordingly; `.pyc` written with **checked-hash
   invalidation** (FAT's 2-second mtime granularity makes mtime-based validation
   lie during fast edit-run cycles).