docs: architecture describes what is built now

kernel (threads, demand paging, TLB shootdowns, dynamic linking, RAM direct map), syscalls, filesystem (/proc, /sys,
/dev), terminals (12, VT handshake, ptys), networking (r8169 through LDLS), LDLS (module sets; Linux code may ship),
devices (what stays in the kernel; hybrid.md's lasting content), boot (the loader's placement of the kernel),
graphics (fbdev, GMMOS, QR 1-40), audio (ALSA over OSS), debugging, usb. New: packages.md (the apk root) and
desktop.md (Xorg on the framebuffer).

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EVRhxi9zpdW2uDUN4FVcao

docs/architecture/usb.md

@@ -21,9 +21,10 @@ The specification is public and the controller is not complicated.
 > BSD is much more valuable as the reference you check yourself against than as
 > the code you paste.
 
-Licensing points the same way: the BSD stacks are BSD-2/3-clause and compatible,
-Linux's drivers are GPL-2.0-only and are not — see
-[../licensing.md](../licensing.md).
+Licensing does not decide it: the BSD stacks are BSD-2/3-clause and compatible, and
+since SchOS became GPL-2.0-or-later Linux's GPL-2.0-only drivers are compatible too
+— see [../licensing.md](../licensing.md). The argument against porting is the
+framework underneath, not the licence.
 
 ## What the spec gives you for free
 
@@ -129,7 +130,8 @@ working one.
   filesystem's next read, by the rule in `blkdev_rw()`: a filesystem that went on
   with missing blocks would be guessing.
 - **HID is keyboards and pointers.** Consumer-control interfaces (volume keys),
-  game pads and the rest are declined. Keyboard LEDs are not driven.
+  game pads and the rest are declined. Caps, Num and Scroll Lock light their LEDs
+  on USB and PS/2 keyboards, one state shared between keyboards.
 - **USB 3 hubs** are not driven: the hub driver speaks the USB 2 hub protocol.
 - **No isochronous transfers**, so no audio and no cameras.
 - **No USB 3 SuperSpeed-specific features** beyond what enumeration needs — the