ROADMAP.md: scope M8 REPL keyboard wiring, design decisions resolved

Not implementation -- documentation-only. M8 is tracked outside Stadium
(FABRIC.md §27.5), so this scoping lives in docs/lithosananke/ROADMAP.md
rather than as new FABRIC.md 4.3.x items.

Read the code before scoping, not assumed: the REPL already works
interactively over serial (sk_repl_run(), repl.c) with working
backspace/echo, and its on-screen text already renders via the existing
VT100 console (vt100_init()/font_8x16.c) independent of both the stroke
font and TrueType work -- neither was ever a REPL-strip prerequisite.
What's actually missing: sk_readline()'s console_getc() is
serial-UART-only, never touches KEY-EVENT (4.3.5f); KEY/?TERMINAL
(io_words.c) are dead stubs (KEY calls a getchar() hardcoded to EOF in
shim.c, ?TERMINAL always returns false).

Resolved design decisions: minimal US-QWERTY scancode->ASCII layout
with shift-state tracking (KEY-EVENT carries no modifier state today);
merge keyboard into console_getc()'s poll with serial staying a
co-equal source, not replaced (the entire acceptance/DoE harness
injects over the serial socket -- breaking that breaks make qemu,
DOE_INJECT, and every screendump technique used throughout 4.3.x); wire
KEY/?TERMINAL to the same merged source for FORTH-79 compliance;
CANVAS viewport sizing last, since it's presentation not input
plumbing. Extended scancodes, autorepeat-as-character-repeat, arrow-key
history explicitly out of scope for the "minimal" bar.

FABRIC.md's existing "not yet scoped" notes (4.3.5f's landing-point
note, 4.3.7f's closing note) updated to point here rather than
duplicating the design content.

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

FABRIC.md

@@ -4387,6 +4387,13 @@ document and committing that amendment as its own item.*
   > scoped. Whether the fix lands in `shim.c`'s `getchar()`, in `io_words.c` under
   > `#ifdef __STARKERNEL__`, or elsewhere is an open question for that later item, not
   > decided here.
+  >
+  > **Now scoped, 2026-08-11 — resolved in `docs/lithosananke/ROADMAP.md`'s M8 section,
+  > not here.** M8 is "tracked outside Stadium" per §27.5, and its console-facing pieces
+  > don't change this document's own scope, so the resolution lives there rather than as
+  > new 4.3.x items. Short answer to the open question above: `io_words.c` under
+  > `#ifdef __STARKERNEL__`, wired to the same merged serial+keyboard source the REPL uses
+  > — see that section for the full design.
 
 - [x] **4.3.6 — Em-square glyph coordinate convention.** `EM-UNITS 1000` (baseline Y=0,
   x-height ≈500, cap-height ≈700, ascender ≈750, descender ≈-250), plus `EM-X`/`EM-Y`/
@@ -4954,6 +4961,17 @@ document and committing that amendment as its own item.*
   > TrueType rendering (4.3.7-4.3.7f) is now complete, adjunct to the stroke font per §27.7's
   > decision #4 -- both text paths coexist. Per this item's own posture (matching 4.3.6g),
   > stopping here before scoping REPL wiring (M8).
+  >
+  > **M8 scoped 2026-08-11 in `docs/lithosananke/ROADMAP.md`, not here** -- per §27.5, M8 is
+  > tracked outside Stadium, so its design decisions live in that roadmap's own M8 section
+  > rather than as new 4.3.x items. Key finding from that scoping pass, worth recording in
+  > this document too since it bears on §27.6's CANVAS/REPL-strip framing: the REPL's
+  > on-screen text already renders via the existing VT100 console
+  > (`console_fb_init()`/`vt100_init()`, baked-in `font_8x16.c`), independent of both the
+  > stroke font and TrueType work above -- neither 4.3.6-4.3.6g nor 4.3.7-4.3.7f was ever a
+  > prerequisite for the REPL strip itself. What's still open for M8 is purely input-side:
+  > `KEY-EVENT` (4.3.5f) isn't yet wired into the REPL's character source
+  > (`console_getc()`), and `KEY`/`?TERMINAL` remain the dead stubs already noted above.
 
   ⋯ *(4.3.x is open-ended — more items get appended here as Console work is scoped item by*
   *item, developed on the fly per §25.0. 4.4 below is unaffected by anything added above*