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>

docs/ch383_audit_log.md

@@ -0,0 +1,14 @@
+# Ch383 Audit Log - Thirty-Four-Draw Third-Binding Extension
+
+- `zsrte34` extends the native-640x480 persistent-Z scene to 34 authenticated draws in 13 epochs, retaining the
+  three runtime texture/CLUT bindings at relocated CBPs `500/504/508`.
+- Local depth-4096 integration passes with 647,303 accepted fragments, 500,072 Z-pass updates, 13 fresh drains,
+  zero drops, exact Z `0/307200`, and exact color `0/166963`.
+- The DE25 host run completed all 1,899 expected records with all palette and texture-fill checks passing and no
+  fragment drops. Its framebuffer bounds were `(46,3)..(634,473)` with 166,963 nonzero pixels.
+- The board dump and the independently traced integration framebuffer are byte-identical at SHA-256
+  `61169f615b327f235405cabb19fff38d3b336c359cd30c498357b6b16338bd19`.
+- Replay-color is exact at `307200/307200`: 647,303 replay fragments, 500,072 Z-pass updates, 166,963 covered
+  pixels, and zero uncovered writes.
+
+Ch383 closes the 34-draw, 13-epoch extension on the timing-closed core. No RTL, SDC, QSF, or Quartus fit changed.