Stabilize first-run cudagraph timing and colorize terminal output

- _cudagraph_plugin: warm up autotune/JIT explicitly before graph capture
  (internal 5-iter warmup is too short), tag fallback markers with the
  failing phase; first-run latency no longer jitters run-to-run.
- _device_guard_plugin (new): set GEMS_VENDOR via torch probe before
  importing flag_gems, avoiding its timeout-less nvidia-smi subprocess
  probe that can hang import in fork-broken environments.
- _pretty_report_plugin (new) + _term_style (new): fold inputs identical
  across all result rows into a legend line, color status/plugin
  tags/markers on the live terminal; run.log is ANSI-stripped and keeps
  upstream SUCCESS/column wording for grep compatibility.
- run_pytest.sh: make USE_FLAGTUNE overridable, group all knobs into a
  config section with Chinese comments, add start/end banners.
- README: document the warmup semantics, new plugins/env vars, and the
  A/B rule that both sides must use the same USE_FLAGTUNE.

_mm_cluster_fix_plugin.py

@@ -92,22 +92,26 @@ def _warmup_load_backend():
             torch.mm(a, b)
             torch.cuda.synchronize()
     except (ImportError, AttributeError) as e:
-        print(f"[mm-cluster-fix-plugin] warmup skipped (benign): {e!r}",
+        from _term_style import tag
+        print(f"{tag('[mm-cluster-fix-plugin]')} warmup skipped (benign): {e!r}",
               file=sys.stderr, flush=True)
     except Exception as e:  # noqa: BLE001
         # e.g. a CUDA error — do NOT hide it; the harness needs to see it.
-        print(f"[mm-cluster-fix-plugin] WARNING: warmup mm failed unexpectedly: {e!r}",
+        from _term_style import tag
+        print(f"{tag('[mm-cluster-fix-plugin]')} WARNING: warmup mm failed "
+              f"unexpectedly: {e!r}",
               file=sys.stderr, flush=True)
 
 
 def pytest_configure(config):
+    from _term_style import tag
     _patch_loaded()
     _warmup_load_backend()
     _patch_loaded()
     guarded = _guarded_modules()
     if guarded:
         print(
-            "[mm-cluster-fix-plugin] guarded cluster_remote_mm_scenario "
+            f"{tag('[mm-cluster-fix-plugin]')} guarded cluster_remote_mm_scenario "
             f"(odd N-tile unmasked OOB) in: {guarded}",
             file=sys.stderr,
             flush=True,
@@ -125,7 +129,7 @@ def pytest_configure(config):
     else:
         # Non-Hopper: the cluster path never runs, so an unpatched state is fine.
         print(
-            "[mm-cluster-fix-plugin] no cluster_remote_mm_scenario found; "
+            f"{tag('[mm-cluster-fix-plugin]')} no cluster_remote_mm_scenario found; "
             "non-Hopper device, guard not needed (no-op).",
             file=sys.stderr,
             flush=True,