fix(forward-log): distinguish histograms from missing-report (v1.5.3)

On machines running histogram-mode units (extensions ending in H,
e.g. H907L1R7.PG0H), every forwarded event was logging "no report"
even though histograms never get auto-exported ASCII reports from
Blastware — making the log look like every forward was misconfigured
when in fact things were working correctly.

Three log states now:

  - Waveform + paired TXT
      → "+ <txt> attached"
  - Waveform without TXT (likely BW config issue)
      → "no report ⚠"
  - Histogram (any flavour)
      → "(histogram, no report expected)"

New is_histogram_event() helper classifies by BW filename extension:
4-char ext ending in H = histogram; old-firmware 3-char extensions
default to non-histogram (safe default — we'd rather flag a missing
report than silently suppress the warning on a real waveform event).

Forwarding logic itself is unchanged — this is purely log clarity.

event_forwarder.py

@@ -101,6 +101,23 @@ def report_path_for(binary_path: str) -> str:
     return binary_path + ".TXT"
 
 
+def is_histogram_event(filename: str) -> bool:
+    """True if the filename's extension marks the file as a Full Histogram
+    event (BW filename scheme: 4-char extensions of the form ``AB0T`` where
+    ``T = H``).  Old-firmware events use 3-char extensions where waveform-vs-
+    histogram is not encoded in the name; we can't tell those apart and
+    return False (the conservative answer — we don't want to suppress
+    "no report" warnings on potentially-waveform old-firmware events).
+
+    Used purely for log clarity — histograms don't get auto-exported BW
+    ASCII reports, so "no report" on a histogram is not a problem to
+    flag.  Forwarding logic itself doesn't depend on this check.
+    """
+    name = os.path.basename(filename)
+    ext = os.path.splitext(name)[1].lstrip(".").upper()
+    return len(ext) == 4 and ext.endswith("H")
+
+
 # ── State file ────────────────────────────────────────────────────────────────
 
 
@@ -513,12 +530,27 @@ def forward_pending(
             counts["forwarded"] += 1
             if txt_path:
                 counts["with_report"] += 1
+
+            # Differentiate three cases in the log so "no report" is only
+            # noisy when something's actually unexpected:
+            #   - waveform + TXT          → "+ <txt> attached"
+            #   - waveform without TXT    → "no report ⚠"  (BW maybe didn't auto-export)
+            #   - histogram (any flavour) → "(histogram, no report expected)"
+            if txt_path:
+                report_token = "+ {} attached".format(os.path.basename(txt_path))
+            elif is_histogram_event(binary_path):
+                report_token = "(histogram, no report expected)"
+            else:
+                report_token = "no report ⚠"
+
             _log(
-                f"[forward] OK  {os.path.basename(binary_path)}  "
-                f"({result.get('filesize', 0)}B, "
-                f"{'with' if txt_path else 'no'} report, "
-                f"inserted={result.get('inserted', 0)}, "
-                f"skipped={result.get('skipped', 0)})"
+                "[forward] OK  {}  ({}B, {}, inserted={}, skipped={})".format(
+                    os.path.basename(binary_path),
+                    result.get("filesize", 0),
+                    report_token,
+                    result.get("inserted", 0),
+                    result.get("skipped", 0),
+                )
             )
         else:
             counts["errors"] += 1