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>

v3/include/README.md

@@ -0,0 +1,54 @@
+# include/
+
+Public headers for the hosted StarForth VM (`src/`). Kernel-only headers
+live under `include/starkernel/`.
+
+**Core VM**
+- `vm.h` — the `VM` struct and all core types (`DictEntry`, `DictPhysics`,
+  stacks, dictionary state); the central header most other files include.
+- `vm_api.h` — external VM API surface.
+- `vm_host.h`, `vm_debug.h`, `startup.h`, `version.h` — host integration,
+  debug utilities, startup sequencing, version string.
+- `cli.h`, `repl.h`, `io.h`, `log.h` — CLI parsing, REPL loop, I/O, logging.
+- `word_registry.h` — word registration system shared by every
+  `src/word_source/*.c` file.
+- `compudynamics.h` — the generic compudynamics module: tuning-word/config
+  lookups (`cd_tuning_word()`, `cd_tuning_vm()`) consumed by `ssm_jacquard.c`.
+
+**Memory / blocks**
+- `memory_management.h`, `dictionary_management.h` — dictionary allocator
+  and search.
+- `block_subsystem.h`, `blkcfg.h`, `blkio.h`, `blkio_factory.h` — logical→
+  physical block mapper and pluggable block I/O backends (file/RAM).
+- `platform_alloc.h`, `platform_lock.h`, `platform_time.h` — platform
+  abstraction shims (hosted vs. kernel allocation/locking/timing).
+
+**Physics-driven adaptive runtime (7 feedback loops)**
+- `physics_runtime.h` — main physics coordinator.
+- `physics_hotwords_cache.h` — Loop #1, execution-heat hot-words cache.
+- `physics_metadata.h` — per-word `DictPhysics` metadata tracking.
+- `physics_pipelining_metrics.h` — Loop #4, word-transition prediction.
+- `physics_execution_hooks.h` — execution instrumentation hook points.
+- `rolling_window_of_truth.h`, `rolling_window_knobs.h` — Loop #2 circular
+  execution-history buffer and its tuning knobs.
+- `inference_engine.h` — Loops #5/#6, window-width and decay-slope
+  statistical inference.
+- `dictionary_heat_optimization.h` — Loop #1 heat counters.
+- `ssm_jacquard.h` — L8 Jacquard steady-state mode selector.
+- `doe_metrics.h` — Design of Experiments (2^7 factorial) metrics.
+- `profiler.h` — performance profiling hooks.
+
+**Arithmetic / codegen**
+- `q48_16.h` — Q48.16 deterministic fixed-point arithmetic (used instead of
+  IEEE-754 float specifically to keep cross-architecture behavior
+  bit-identical).
+- `math_portable.h` — portable math helpers.
+- `arch_detect.h`, `starforth_config.h` — architecture detection and the
+  build-flag fallback-default layer (used when a `.c` file is compiled by
+  hand without `make`).
+- `vm_asm_opt.h`, `vm_asm_opt_arm64.h`, `vm_asm_opt_riscv64.h`,
+  `vm_inner_interp_asm.h`, `vm_inner_interp_arm64.h`,
+  `vm_inner_interp_riscv64.h` — per-architecture assembler-optimized inner
+  interpreter (`USE_ASM_OPT=1`).
+
+See `include/starkernel/README.md` for the bare-metal kernel headers.