Rename FABRIC series: FABRIC.md->0, FABRIC-2.md->1, FABRIC-3.md->2, FABRIC-4.md unchanged

FABRIC.md -> FABRIC-0.md
FABRIC-2.md -> FABRIC-1.md
FABRIC-3.md -> FABRIC-2.md (the current/living document)
FABRIC-4.md unchanged (new #3 to follow separately)

Every cross-reference repo-wide updated to match, including doc-comment
citations inside kernel source (.c/.h) files -- done via an ordered
placeholder substitution (FABRIC-3.md->placeholder2, FABRIC-2.md->
placeholder1, FABRIC.md->placeholder0, then placeholders resolved to
final names) in a single pass per file to avoid double-shifting
already-renamed references.

One line in capsules/font.4th grew past the 64-char block-format limit
as a side effect of the longer filename; shortened it and reverified
with mkcapsule --lint (34/34 pass) before rebuilding.

Verified 3-arch boot to ok> (amd64/aarch64/riscv64, each in the
foreground) after the fix; logs and DoE CSVs from this session's
verification runs included per this repo's own audit-artifact
convention.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_019YcT3H2PQeyujrzjqS3Var

src/word_source/keyboard_words.c

@@ -7,7 +7,7 @@
   Licensed under the StarForth License, Version 1.0
 */
 
-/* keyboard_words.c — raw scancode-ring diagnostic word (FABRIC.md item
+/* keyboard_words.c — raw scancode-ring diagnostic word (FABRIC-0.md item
  * 4.3.5). Kernel-only, amd64-only; no-op elsewhere. */
 
 #include "include/keyboard_words.h"
@@ -121,7 +121,7 @@ static void kbw_vdebug(VM *vm)
  * field already lives in the same Linux keycode namespace; `value` is
  * mapped 1:1 except autorepeat (value=2), folded into "still pressed"
  * here since this checkpoint's shape only distinguishes press/release. */
-/* FABRIC.md item 4.4v: shared C-level implementation, so the REPL
+/* FABRIC-0.md item 4.4v: shared C-level implementation, so the REPL
  * keyboard bridge (repl.c) and the KEY-EVENT FORTH word below poll the
  * exact same converged event stream rather than each re-deriving the
  * per-arch translation kbw_key_event's own doc comment already explains
@@ -166,7 +166,7 @@ static void kbw_key_event(VM *vm)
     }
 }
 
-/* ALT+TAB ( -- ): FABRIC.md item 4.4y-revised. Programmatic equivalent of
+/* ALT+TAB ( -- ): FABRIC-0.md item 4.4y-revised. Programmatic equivalent of
  * the physical Alt+TAB interception (repl.c's sk_kbd_getc()) -- both call
  * console_fb_toggle_graphics(), so there is exactly one state-machine
  * transition, invoked two ways. */