Initial commit: Schunix as it stands before the SchOS rename

An x86-64 operating system built from xv6, now largely rewritten: SMP,
a copy-on-write root filesystem (SchFS), PCI/USB/virtio drivers, a TTF
rasteriser, and a Linux-numbered syscall ABI.

No history before this point -- the tree was never under version control.
This commit exists so the rename that follows has something to undo to.

projects/README.md

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+# projects/
+
+Things that run **on** Schunix rather than things that **are** Schunix.
+
+Everything above this directory — `kernel/`, `boot/`, `lib/`, `cmd/`,
+`include/` — is the operating system: it boots, it owns the hardware, and it
+is one program that either works or does not. Everything in here is an
+ordinary program that talks to it through syscalls, exactly as `toybox` does.
+
+The split exists because the alternative gets bad quickly. A compositor,
+a window manager and a desktop are each larger than the kernel will be for a
+long time. Grown inside the OS tree they would blur into it: a compositor
+would start reaching into kernel headers because they are right there, the
+build would grow a dependency from the kernel to a GUI, and "does Schunix
+boot" would stop having a clear answer. Keeping them separate forces the
+boundary to be a real interface — syscalls and protocols — rather than a
+shared header nobody meant to share.
+
+Concretely, code in here:
+
+- links against the sysroot's libc, never against kernel headers
+- talks to the kernel only through syscalls and `/dev`
+- can be built, run and debugged without rebuilding the kernel
+- may be split into its own repository later without untangling anything
+
+## What lives here
+
+| Directory  | What it is                                                      |
+|------------|-----------------------------------------------------------------|
+| `schcom/`  | Schunix Compositor. Owns the display, composites clients, routes input. |
+| `schwm/`   | Schunix Window Manager. Window placement, decoration, focus, on top of Schcom. |
+| `schde/`   | Schunix Desktop Environment. Panel, launcher, settings, file manager. |
+| `schinst/` | The installer, the installation environment, and `.sip` tooling. |
+| `schfs-linux/` | SchFS as a filesystem for Linux. FUSE first, a kernel module later. |
+
+**`schfs-linux/` is written to stand on its own.** It does not mention Schunix
+anywhere, and that is deliberate rather than an oversight: it is intended to be
+the first piece released, and it has to make sense to somebody who has never
+heard of the OS it came from — a filesystem is judged as a filesystem. The
+connection can be made later, once there is a finished system to connect it to.
+
+Practically, that means anything added there needs its own licence header, its
+own README framing, and no cross-references into this tree. It shares the
+*format* with `kernel/fs/schfs/`, not the prose.
+
+They stack: SchDE needs SchWM needs Schcom needs the kernel. Nothing points
+the other way, and nothing here is a dependency of the kernel build.
+
+## Status
+
+All four are scoped and none is started. What each is waiting on is written
+in its own README, and the ordering is in `docs/roadmap.md`.
+
+The short version: Schcom cannot start until the kernel has **unix domain
+sockets** (for the client protocol and for passing buffer handles) and **raw
+input events** (a `/dev/input` that bypasses the tty line discipline).
+Shared memory and framebuffer mmap are already done.