starkernel: color the console prompt (FABRIC.md item 4.4h)

console.c's emit_prefix() now wraps [VMName] (brackets included) in
FABRIC.md 4.4's locked orange (0xFFA500), and repl.c's two "ok> "
call sites send FABRIC.md 4.4's locked cyan (0x55FFFF), both as real
SGR escape sequences through the existing font_8x16.c/vt100.c pipeline
-- 4.4b already established this needs no dependency on TTF-TEXT/4.4j.
Sent through both raw_putc() (serial) and vt100_putc() (framebuffer),
matching the existing dual-path pattern, so an ANSI-aware serial
terminal renders the same colors as the framebuffer.

Three-arch verified: amd64/aarch64/riscv64 all reach ok>, POST
Failed: 0, identical dict-hashes. Color applies correctly to any VM
name (confirmed via the [Hermes]-prefixed PARITY:BIRTH line in all
three logs, not just [Hera]). amd64 screendump confirms the rendered
colors directly.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

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