Verify turtle.4th rendering live, revert overdue ART-STRESS-CAMPAIGN disable

Disabled capsules/artemis/init.4th block 4170's ART-STRESS-CAMPAIGN -- its
own comment already said to revert to disabled once the K-invariant/
heartbeat verification run (item 4.6, closed earlier this session) was
done. This was the actual ~25-30 minute wall blocking interactive REPL
access, unrelated to any DoE mechanism.

Verified capsules/turtle.4th and capsules/sdk.4th live in a gtk-display
QEMU session: a red hexagon (6 100 POLYGON) and a green self-intersecting
star (100 STAR) both render with correct geometry and color. Screenshot in
evidence/amd64/.

Two real obstacles found and worked around along the way: CS's full-
framebuffer PLOT loop is far slower under TCG than previously documented
(closer to 20+ minutes than "slow"), and the kernel's heartbeat CSV logging
draws to the same console surface PLOT writes pixels to, overwriting
drawings within a fraction of a second unless silenced first with the
existing HB-OFF word. Both HOWTOs updated to record this.

Re-verified full three-arch acceptance boot (POST, DoE, parity) with the
ART-STRESS-CAMPAIGN change: 1012/0/0 and matching dict_hash on all three,
identical to the pre-change baseline.

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

docs/working/architecture/SDK-HOWTO-20260819.md

@@ -88,8 +88,11 @@ Everything from `turtle.4th` and `doe.4th` is also available after loading
   identically, `dict_hash` unchanged from the pre-`sdk.4th` baseline on
   all three (expected — `sdk.4th` isn't autoloaded, so it cannot affect
   boot-time dictionary content).
-- Not yet driven interactively through a live REPL — same practical
-  limitation as `turtle.4th`'s own HOWTO documents (the DoE campaign that
-  auto-runs on every kernel boot blocks the REPL for ~25–30 minutes before
-  serial commands can reach it). The FORTH logic is verified; the
-  interactive load-and-run experience is not.
+- **Driven interactively 2026-08-19**, live over the QEMU serial socket:
+  `S" sdk.4th" EXEC` loads cleanly (`SDK v1.9.0 (scoping)` banner prints),
+  and the re-exported `turtle.4th` renders correctly (see that HOWTO's own
+  updated verification section for the screenshot and the two practical
+  gotchas found along the way — `ART-STRESS-CAMPAIGN` was the actual
+  ~25–30 minute wall, not any DoE mechanism, and `HB-OFF` is needed before
+  drawing anything since heartbeat logging shares the same console surface
+  `PLOT` draws to).