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

include/starkernel/capsule_mint.h

@@ -9,7 +9,7 @@
 
 /**
  * capsule_mint.h - MINT: mint a fresh identity onto a blank thumbdrive
- * (FABRIC-3.md §F.8/§F.19), the last piece of the original Tripod
+ * (FABRIC-2.md §F.8/§F.19), the last piece of the original Tripod
  * vision. Writes a real keypair, a Zuse-signed cert, and a minimal
  * working default personality -- everything RUNCAP (capsule_runcap.h)
  * and CERTVERIFY need at a later attach.
@@ -87,7 +87,7 @@ typedef enum {
  *                   internal "refuse to overwrite" re-check, which
  *                   otherwise repeats the exact same full BOT read
  *                   sequence a second time for no reason (found live,
- *                   FABRIC-3.md §F.25/§F.26: the redundant check was
+ *                   FABRIC-2.md §F.25/§F.26: the redundant check was
  *                   mistaken for a hang before the real cause -- leaked
  *                   `tail -f` processes from repeated hard kills during
  *                   the same debugging session -- was found). Pass 0 from