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/arch/riscv64/arch.c

@@ -69,7 +69,7 @@ void arch_early_init(void)
      * activated here, per its own load_cr3() no-op outside __x86_64__) and
      * has no present use for virtual memory on this ISA, so there is no
      * reason to inherit firmware's Sv57 mapping -- which is confirmed to
-     * have at least one hole (PLIC_THRESHOLD, FABRIC.md item 4.3.5a).
+     * have at least one hole (PLIC_THRESHOLD, FABRIC-0.md item 4.3.5a).
      * ExitBootServices() has already completed several checkpoints before
      * this function runs (ConOut/GOP done, BootServices exited per the
      * "[CKPT 008]" trace), so nothing downstream depends on firmware's

src/starkernel/arch/riscv64/timer.c

@@ -16,7 +16,7 @@
  * mixing the two counters would compare unrelated clocks; and `cycle` has no
  * discoverable frequency, so every heartbeat variance and TIME-TRUST figure
  * riscv64 produced before this was measured against a wrong expected interval
- * (FABRIC.md §16.2). Figures from before and after are not comparable.
+ * (FABRIC-0.md §16.2). Figures from before and after are not comparable.
  */
 
 #include "timer.h"
@@ -27,7 +27,7 @@
 #include <stdint.h>
 #include <string.h>
 
-/* FABRIC-3.md §I.5, 2026-09-04: real hypervisor-vs-hardware detection.
+/* FABRIC-2.md §I.5, 2026-09-04: real hypervisor-vs-hardware detection.
  * s_cal.vm_mode was hardcoded to 1 unconditionally below -- see
  * aarch64/timer.c's own running_under_hypervisor() doc comment for why
  * that's wrong to reuse as a general "are we in QEMU" signal elsewhere
@@ -265,7 +265,7 @@ const timer_calibration_record_t *timer_calibration_record(void)
 /**
  * @brief Read the raw counter the riscv64 heartbeat is paced against.
  *
- * Item 0.8 (FABRIC.md §25.1): the shared heartbeat.c now owns
+ * Item 0.8 (FABRIC-0.md §25.1): the shared heartbeat.c now owns
  * heartbeat_init()/heartbeat_tick()/heartbeat_service()/heartbeat_ticks()/
  * heartbeat_trust()/heartbeat_state(). This is the one piece that stays
  * per-architecture -- the same @c rdtime() the timer deadline is armed