Reorganize source tree: kernel/, v3/, v4/ split and board infrastructure

Source tree reorganization:
- Move StarForth v3 engine to v3/ (src/, include/, Makefile)
- Move kernel to kernel/ (src/, include/, linker/, Makefile)
- Create v4/ skeleton for F18-ISA golden model (DECOMPOSITION.md, JUSTIFICATION.md)
- Move FABRIC-0..4.md to docs/fabric/
- Move ONTOLOGY.md and ROADMAP.md to docs/

Board infrastructure:
- Add boards/ser5/, boards/raspi/, boards/milkv/, boards/zynq7020/
- Each board has board.mk (ISA, CPU flags, boot recipe) and README.md
- Root Makefile becomes thin dispatcher: boot_image, all, clean, docs take TARGET
- make boot_image TARGET=SER5|RASPI|MILKV builds one GPT/MBR image per board
- ZYNQ7020 target exists but stops with clear error (ARMv7 port not built yet)
- scripts/mkdiskimage.sh builds disk images for all boards

Docs pipeline:
- docs/book/ with LaTeX master (main.tex) and Makefile
- pandoc converts Markdown to LaTeX at build time
- Two Lua filters: table-widths.lua (wide tables wrap), code-breaks.lua (inline code breaks)
- make docs builds single PDF (754 pages, 0 missing characters)
- make docs TARGET=<board> adds board appendix
- build/docs/<book|board>/meta.tex stamps git commit into PDF

Bug fixes:
- 42 include paths that only worked by accident now use correct relative paths
- clang-18 hardcode replaced with configurable CC variable (fixed aarch64 build)
- Pi 5: kernel_2712.img linked at 0x80000, .bss zeroed, memory reserved
- Doxyfile, .clang-tidy, README.md, Kconfig paths updated

Verified:
- Hosted v3 build passes 1012 tests, 0 failures
- SER5 image boots in QEMU (OVMF), POST passes, K exact (65536 = Q48_ONE)
- Milk-V image boots in QEMU (OpenSBI + U-Boot + bootefi), POST passes
- make clean TARGET=<board> removes only that board and its ISA objects
- make all builds all boards, hosted v3, and docs in one run

Co-authored-by: Junie <junie@jetbrains.com>

kernel/include/starkernel/vm_uuid.h

@@ -0,0 +1,101 @@
+/*
+  StarForth — Steady-State Virtual Machine Runtime
+
+  Copyright (c) 2023–2025 Robert A. James
+  All rights reserved.
+
+  This file is part of the StarForth project.
+
+  Licensed under the StarForth License, Version 1.0 (the "License");
+  you may not use this file except in compliance with the License.
+
+  You may obtain a copy of the License at:
+      https://github.com/star.4th@proton.me/StarForth/LICENSE.txt
+
+  This software is provided "AS IS", WITHOUT WARRANTY OF ANY KIND,
+  express or implied, including but not limited to the warranties of
+  merchantability, fitness for a particular purpose, and noninfringement.
+
+ See the License for the specific language governing permissions and
+ limitations under the License.
+
+ */
+
+/**
+ * vm_uuid.h - 128-bit VM identifiers (FABRIC-0.md punch list item 3.8)
+ *
+ * Replaces capsule_birth.c's monotonic uint32_t vm_id with a wider,
+ * RFC-4122-shaped identifier. NOT real randomness: this kernel has no RNG
+ * source at all (checked directly against QEMU 10.2.1's actual CPU feature
+ * set -- amd64 RDRAND and riscv64 Zkr are both available, aarch64 has
+ * neither RNDR nor any RNG property on any CPU model including "max"), and
+ * Captain Bob ruled a uniform fallback across all three ISAs rather than a
+ * per-architecture split. Values are generated by a deterministic PRNG
+ * (splitmix64) seeded from the Mama capsule's content hash -- the same
+ * capsule booted twice produces the same ID sequence, preserving the
+ * run-to-run reproducibility this project has relied on everywhere else
+ * (the dict_hash regression check after every prior item this session).
+ */
+
+#ifndef STARKERNEL_VM_UUID_H
+#define STARKERNEL_VM_UUID_H
+
+#ifdef __STARKERNEL__
+
+#include <stdint.h>
+
+typedef struct {
+    uint64_t hi;
+    uint64_t lo;
+} VMUuid;
+
+/*
+ * vm_uuid_hera - The fixed, reserved identifier for Hera (patron zero,
+ * item 3.6; VM 0 in the pre-item-3.8 scheme). Not drawn from the pool --
+ * capsule_birth.c's KILL logic ("Hera cannot be killed") and the fleet
+ * heat-fanout parent-chain sentinel (capsule_run.h's `parent_vm_id`
+ * comment: "self-referential, parent_vm_id == vm_id == 0") both depend on
+ * Hera's id being a fixed, cheaply-comparable value, exactly as 0 was
+ * before this item. All-zero.
+ */
+VMUuid vm_uuid_hera(void);
+int    vm_uuid_is_hera(VMUuid id);
+
+/*
+ * vm_uuid_none - Sentinel meaning "no id" / "slot not in use." All-ones --
+ * NOT all-zero, because all-zero is Hera's reserved value (item 3.8 caught
+ * this collision before writing any code that could have repeated the
+ * STADIUM_CONTAINS_NONE mistake at a new site).
+ */
+VMUuid vm_uuid_none(void);
+int    vm_uuid_is_none(VMUuid id);
+
+int vm_uuid_equal(VMUuid a, VMUuid b);
+
+/*
+ * vm_uuid_pool_init - Seed the generator. Call once, after the Mama
+ * capsule's content hash is known (right after capsule_birth_mama()
+ * succeeds) and before the first non-Hera VM birth. Idempotent to call
+ * again (re-seeds and refills), though nothing does today.
+ */
+void vm_uuid_pool_init(uint64_t seed);
+
+/*
+ * vm_uuid_next - Pop the next id from the pre-filled FIFO pool, refilling
+ * with a fresh batch (continuing the same deterministic splitmix64 stream)
+ * when empty. If called before vm_uuid_pool_init() (not the intended path),
+ * self-seeds from a fixed default rather than returning garbage -- flagged
+ * as a safety net, not normal use.
+ */
+VMUuid vm_uuid_next(void);
+
+/*
+ * vm_uuid_format - Writes the RFC-4122-shaped string
+ * "xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx" (36 chars + NUL) into buf.
+ * @param buf  Caller-provided buffer, at least 37 bytes.
+ */
+void vm_uuid_format(VMUuid id, char *buf);
+
+#endif /* __STARKERNEL__ */
+
+#endif /* STARKERNEL_VM_UUID_H */