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>

rtl/platform/tile_ram_cdc.sv

@@ -85,6 +85,7 @@ module tile_ram_cdc (
     // Three stages let us compute an edge detector against the
     // already-resampled bits ([2] ^ [1]), giving the wr_pulse a full
     // dclk cycle of bclk_wr_index/data stability before we sample.
+    (* altera_attribute = "-name SYNCHRONIZER_IDENTIFICATION FORCED" *)
     logic [2:0] toggle_sync;
     always_ff @(posedge dclk or negedge dreset_n) begin
         if (!dreset_n)