CCL allreduce: rename to lrab_hierarchical_allreduce + descriptive plots

Rename the intercube all-reduce identity to lrab_hierarchical_allreduce
(module, config key, distributed test) so the name reflects both levels
it implements: LRAB intra-SIP (local reduce to center root + broadcast)
and the hierarchical inter-SIP topology exchange (ring/torus/mesh).
ADR-0032 slug kept as the stable decision id; pure rename, no logic change.

Also in this batch:
- ADR-0032 (EN+KO): document the shipped center-root bidirectional reduce
  (doc was stale corner-root); annotate ccl.yaml root_cube as a placeholder.
- Rename allreduce + pe2pe latency plots to descriptive, title-matching
  filenames and retitle the in-plot headings; drop overview/overview_log.
- Point the PPTX image refs at the new plot names.

Doc + derived-artifact + rename only; no simulation behavior changed.

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

tests/test_allreduce_buffer_kind_sweep.py

@@ -3,7 +3,8 @@
 Parametrized over (buffer_kind, n_elem). Each case runs the standard
 config-driven allreduce app and writes a JSON row to a shared staging
 dir; the conftest sessionfinish hook (added in Phase 1) aggregates
-rows into ``docs/diagrams/allreduce_latency_plots/buffer_kind_sweep.png``.
+rows into ``docs/diagrams/allreduce_latency_plots/
+AllReduce_LRAB_2Dtorus_6SiP_2x3_with_TCM_SRAM_HBM.png``.
 
 Pre-Phase-2: the three buffer-kind lines overlap exactly because slot
 access is latency-free today. Post-Phase-2 they spread out (tcm
@@ -36,6 +37,8 @@ _ELEM_BYTES_F16 = 2
 _OUT_DIR = (Path(__file__).parent.parent / "docs" / "diagrams"
             / "allreduce_latency_plots")
 _ROWS_DIR = _OUT_DIR / "_buffer_kind_rows"
+# Descriptive output stem (shared by the .png and .csv).
+_OUT_STEM = "AllReduce_LRAB_2Dtorus_6SiP_2x3_with_TCM_SRAM_HBM"
 
 
 def _bk_params():
@@ -55,7 +58,7 @@ def test_buffer_kind_allreduce_one(tmp_path, buffer_kind, n_elem):
         sub,
         sip_topology="torus_2d",
         n_sips=6,
-        algorithm="intercube_allreduce",
+        algorithm="lrab_hierarchical_allreduce",
         sip_w=3, sip_h=2,
         n_elem_override=n_elem,
     )
@@ -64,7 +67,7 @@ def test_buffer_kind_allreduce_one(tmp_path, buffer_kind, n_elem):
         ccl_cfg = yaml.safe_load(f)
     ccl_cfg.setdefault("defaults", {})["buffer_kind"] = buffer_kind
     ccl_cfg.setdefault("algorithms", {}).setdefault(
-        "intercube_allreduce", {},
+        "lrab_hierarchical_allreduce", {},
     )["buffer_kind"] = buffer_kind
     with open(ccl_path, "w") as f:
         yaml.dump(ccl_cfg, f, default_flow_style=False)
@@ -81,7 +84,7 @@ def test_buffer_kind_allreduce_one(tmp_path, buffer_kind, n_elem):
     ) as ctx:
         result = run_allreduce(
             ctx, engine, spec,
-            algorithm="intercube_allreduce", ccl_yaml=ccl_path,
+            algorithm="lrab_hierarchical_allreduce", ccl_yaml=ccl_path,
         )
         assert result["ok_cubes"] > 0
 
@@ -108,7 +111,7 @@ def test_buffer_kind_allreduce_one(tmp_path, buffer_kind, n_elem):
 
 
 def aggregate_buffer_kind_plot() -> bool:
-    """Read per-config rows and emit buffer_kind_sweep.png + CSV.
+    """Read per-config rows and emit the descriptive .png + .csv (_OUT_STEM).
 
     Called from conftest.pytest_sessionfinish (controller-only).
     Returns True if rows were aggregated.
@@ -141,7 +144,7 @@ def aggregate_buffer_kind_plot() -> bool:
     _bytes_fmt = FuncFormatter(_fmt_bytes)
 
     _OUT_DIR.mkdir(parents=True, exist_ok=True)
-    with open(_OUT_DIR / "buffer_kind_sweep.csv", "w",
+    with open(_OUT_DIR / f"{_OUT_STEM}.csv", "w",
               newline="", encoding="utf-8") as f:
         w = csv.DictWriter(f, fieldnames=[
             "buffer_kind", "sip_topology", "n_sips", "n_elem",
@@ -172,13 +175,13 @@ def aggregate_buffer_kind_plot() -> bool:
     ax.set_xlabel("Bytes per PE (log scale)")
     ax.set_ylabel("Time (ns)")
     ax.set_title(
-        "Allreduce torus_2d (6 SIPs, 3×2) — IPCQ slot memory tier"
+        "AllReduce_LRAB_2Dtorus_6SiP(2x3) — IPCQ memory (SRAM, TCM, HBM)"
     )
     ax.grid(True, alpha=0.3)
     ax.legend()
     ax.xaxis.set_major_formatter(_bytes_fmt)
     fig.tight_layout()
-    fig.savefig(_OUT_DIR / "buffer_kind_sweep.png", dpi=130)
+    fig.savefig(_OUT_DIR / f"{_OUT_STEM}.png", dpi=130)
     plt.close(fig)
 
     for p in row_files:
@@ -191,6 +194,6 @@ def aggregate_buffer_kind_plot() -> bool:
     except OSError:
         pass
 
-    print(f"\nWrote {_OUT_DIR / 'buffer_kind_sweep.png'} "
+    print(f"\nWrote {_OUT_DIR / f'{_OUT_STEM}.png'} "
           f"from {len(records)} rows")
     return True