tl.composite: fused epilogue ops with per-op scope

Extend tl.composite() with an ordered epilogue list. Each op carries
a scope flag - output_tile (default, runs once per (m,n) before
STORE), k_tile (every K-tile right after GEMM), or kernel. Plan
generator slots MATH stages by scope; pe_math reuses pe_dma's
local-loop pattern so chained epilogues (bias->relu) skip the port
hop. op_log captures per-stage params for telemetry. Topology
gains a gemm->math edge (snapshot test updated).

API stays backward-compatible - `epilogue=` is opt-in.

Example:
    h = tl.composite(
        op="gemm", a=a, b=b, out_ptr=int(out),
        epilogue=[
            {"op": "dequant", "scale": s_per_k, "scope": "k_tile"},
            {"op": "bias",    "bias":  bias_vec},
            {"op": "relu"},
            {"op": "scale",   "factor": 0.5},
        ],
    )
    tl.wait(h)

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/kernbench/sim_engine/op_log.py

@@ -51,11 +51,15 @@ class OpLogger:
         record_end fires.
         """
         snap: dict[str, Any] = {}
-        # TileToken (ADR-0021 pipeline) — capture which stage this is.
+        # TileToken (ADR-0021 pipeline) — capture which stage this is and its
+        # per-stage params (e.g. op_kind/scope for epilogue MATH stages) so
+        # we can recover them at record_end even after the token advances.
         try:
             stage = getattr(msg, "current_stage", None)
             if stage is not None:
                 snap["stage_type"] = stage.stage_type.name
+                if isinstance(getattr(stage, "params", None), dict):
+                    snap["stage_params"] = dict(stage.params)
         except Exception:
             pass
         self._pending[id(msg)] = {
@@ -78,6 +82,11 @@ class OpLogger:
         stage_type = snap.get("stage_type")
         if stage_type is not None:
             params = dict(params)
+            # Merge per-stage params (e.g. op_kind, scope) captured at start.
+            stage_params = snap.get("stage_params")
+            if isinstance(stage_params, dict):
+                for k, v in stage_params.items():
+                    params.setdefault(k, v)
             params["stage_type"] = stage_type
             if op_name == "TileToken":
                 op_name = f"TileToken/{stage_type}"