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/starkernel/vm/host/shim.c

@@ -418,7 +418,7 @@ void sf_mutex_destroy(sf_mutex_t *mutex) {
  * acquiring the mutex is always immediate and guaranteed to succeed.
  *
  * This no-op is correct only as long as nothing running in interrupt
- * context mutates the structure a given lock protects (FABRIC.md §21.2,
+ * context mutates the structure a given lock protects (FABRIC-0.md §21.2,
  * §25.1 item 0.9). If that ever stops being true, making this a real
  * spinlock is not the fix: a single hart taking an interrupt while
  * already holding the lock would spin against itself and deadlock. The
@@ -1107,7 +1107,7 @@ int puts(const char *s) { console_println(s ? s : ""); return 0; }
 int putchar(int c) { console_putc((char)c); return c; }
 /** @brief Kernel @c putc(): ignores stream, same as @c putchar(). GCC's -O2
  *  folds @c putchar(c) / @c fputc(c, stdout) call sites into @c putc(c, stdout)
- *  (FABRIC.md item 4.5d) -- this symbol was never needed at -O0 because that
+ *  (FABRIC-0.md item 4.5d) -- this symbol was never needed at -O0 because that
  *  fold pass is inactive there. */
 int putc(int c, FILE *stream) { (void)stream; return putchar(c); }
 /** @brief Kernel @c fflush(): no-op (console writes are synchronous); returns 0. */
@@ -1246,7 +1246,7 @@ const unsigned short ** __ctype_b_loc(void) {
  *  servicing, no echo). See fgets()'s own doc comment on shim_console_vm(). */
 int getchar(void) { return sk_console_getkey(shim_console_vm()); }
 /** @brief Kernel @c getc(): ignores stream, same as @c getchar(). GCC's -O2
- *  folds @c getchar() call sites into @c getc(stdin) (FABRIC.md item 4.5d) --
+ *  folds @c getchar() call sites into @c getc(stdin) (FABRIC-0.md item 4.5d) --
  *  this symbol was never needed at -O0 because that fold pass is inactive
  *  there. */
 int getc(FILE *stream) { (void)stream; return getchar(); }