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

tools/ttftest.c

@@ -8,7 +8,7 @@
 */
 
 /**
- * ttftest.c — Host-side unit test for src/starkernel/hal/ttf.c (FABRIC.md
+ * ttftest.c — Host-side unit test for src/starkernel/hal/ttf.c (FABRIC-0.md
  * item 4.3.7). No QEMU needed, same pattern as tools/README.md's fbtest.c
  * entry (that file is itself missing from tools/ — stale doc, reported
  * separately, not fixed here).
@@ -58,7 +58,7 @@ static void check_eq_i(const char *what, uint32_t cp, long got, long want) {
 
 /* Outline expectations (4.3.7a), independently computed by a from-scratch
  * Python outline decoder (tools/../../tmp .../ttf_outline_ref.py, not
- * committed, reproducible from FABRIC.md's 4.3.7a completion note) that
+ * committed, reproducible from FABRIC-0.md's 4.3.7a completion note) that
  * shares no code with ttf.c. '.' and '0' are simple glyphs; 'A' is simple
  * with two contours; 'a' is a translation-only composite (2 components). */
 typedef struct {