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/capsule_console.h

@@ -0,0 +1,49 @@
+/*
+  StarForth — Steady-State Virtual Machine Runtime
+
+  Copyright (c) 2023–2025 Robert A. James
+  All rights reserved.
+
+  Licensed under the StarForth License, Version 1.0
+*/
+
+/**
+ * capsule_console.h - Bare console-VM birth (FABRIC-2.md Phase F,
+ * 2026-08-28): a minimal VM whose only job is loading
+ * common:messaging.4th and being the physical REPL's relay target
+ * (sk_repl_dispatch_line(), repl.c) for a paired user VM
+ * (capsule_runcap_birth(), capsule_runcap.h). Not identity-bearing
+ * content -- no thumbdrive read, fixed embedded source, same
+ * heap-built-single-entry-directory shape RUNCAP already established
+ * (§F.6/§F.18), just with compile-time content instead of a devblock
+ * read.
+ */
+
+#ifndef STARKERNEL_CAPSULE_CONSOLE_H
+#define STARKERNEL_CAPSULE_CONSOLE_H
+
+#ifdef __STARKERNEL__
+
+#include "starkernel/capsule_run.h"
+#include "starkernel/vm_uuid.h"
+
+/**
+ * capsule_console_birth - Birth a bare console VM.
+ *
+ * @param console_name  Symbolic name for the new VM -- by convention
+ *                       the same name a user's own identity uses (e.g.
+ *                       "CaptBob"); sk_repl_dispatch_line() looks for a
+ *                       live "<name>~user" counterpart to decide
+ *                       whether a given active VM is a console.
+ * @param parent         Who is birthing this VM (FABRIC-2.md §H.12 step 7)
+ *                       -- passed straight through to capsule_birth_baby().
+ * @param out_vm_id      Output: assigned VM ID.
+ * @param out_vm_ctx     Output: new VM context (may be NULL).
+ * @return CAPSULE_RUN_OK on success, error code otherwise.
+ */
+CapsuleRunResult capsule_console_birth(const char *console_name, VMUuid parent,
+                                        VMUuid *out_vm_id, void **out_vm_ctx);
+
+#endif /* __STARKERNEL__ */
+
+#endif /* STARKERNEL_CAPSULE_CONSOLE_H */