Snapshot: fog implementation + fidelity tooling baseline (pre bilinear-clamp fix)

Per-vertex GS fog end-to-end (gs_stub emit incl. persp_emit5, gs_prim_list_feeder
XYZ2->XYZF2 on PRIM.FGE, gs_make_sh3_scheduler_fixture.py F/FGE packing), new fog
TBs, fidelity attribution tooling. Functional baseline before removing the dead
bilinear lerp8 clamps (Codex: 161-node comb loop -> -0.042ns setup fail).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

tools/scp_zsrt139f33_to_board.sh

@@ -0,0 +1,28 @@
+#!/bin/sh
+# Ch428: accepted Ch427 baseline plus the recovered 256x256 PSMT8
+# character-detail triangle-list family.  No RBF change is required.
+set -eu
+DEST="${1:-terasic@192.168.50.161:~}"
+ROOT="$(cd "$(dirname "$0")/.." && pwd)"
+DATA="$ROOT/sim/data/top_psmct32_raster_demo"
+EPOCHS="$DATA/sh3_zsrt139f33_epochs.txt"
+
+FILES="$ROOT/tools/ps2_sh3_sched.c $EPOCHS"
+add_file() {
+    case " $FILES " in
+        *" $1 "*) ;;
+        *) FILES="$FILES $1" ;;
+    esac
+}
+
+while read -r k idx tbp cbp tex lpddr size crc list words records reuse pal palsum rest; do
+    case "$k" in ''|'#'*) continue ;; META) continue ;; esac
+    add_file "$DATA/$tex"
+    add_file "$DATA/$list"
+    [ "$pal" = "-" ] || add_file "$DATA/$pal"
+done < "$EPOCHS"
+
+for f in $FILES; do
+    [ -f "$f" ] || { echo "MISSING: $f" >&2; exit 1; }
+done
+exec scp $FILES "$DEST"