feat: render ">100" for above-range ZC Freq instead of "—"

BW writes ">100 Hz" for ZC Freq when the zero-crossing algorithm sees a
peak too fast to count — the device's reporting ceiling is 100 Hz on
V10.72.  Our parser fell back to None via _parse_number (which requires
a leading digit), so the PDF rendered "—" where BW shows ">100".

Mirrors the OORANGE/saturated pattern already used for PPV and PSPL:
parser stores the threshold (100.0) on zc_freq_hz + sets a new
zc_freq_above_range flag.  Projection carries the flag through to the
sidecar; PDF renderer prepends ">" when set.

Affects both per-channel stats tables (waveform + histogram variants)
and the mic block's ZC Freq row.

Verified on the real T190LD5Q.LK0W fixture: Tran zc_freq_hz=100.0
above_range=True; Vert/Long (normal values) above_range=False; "N/A"
still produces zc_freq_hz=None which renders as "—" (unchanged).

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

sfm/report_pdf.py

@@ -99,6 +99,7 @@ class ReportData:
     mic_pspl_time_s:        Optional[float] = None
     mic_pspl_when_str:      Optional[str] = None    # histogram absolute date+time, BW-formatted
     mic_zc_freq_hz:         Optional[float] = None
+    mic_zc_freq_above_range: bool           = False
     mic_channel_test_result: Optional[str] = None
     mic_channel_test_freq_hz: Optional[float] = None
     mic_channel_test_amp_mv: Optional[float] = None
@@ -216,7 +217,8 @@ def gather_report_data(
             # Inverse of the dBL formula → psi.  Mirrors waveform_codec convention.
             rd.mic_pspl_psi = DBL_REF_PSI * (10 ** (rd.mic_pspl_dbl / 20))
         rd.mic_pspl_time_s = mic.get("time_of_peak_s")
-        rd.mic_zc_freq_hz  = mic.get("zc_freq_hz")
+        rd.mic_zc_freq_hz             = mic.get("zc_freq_hz")
+        rd.mic_zc_freq_above_range    = bool(mic.get("zc_freq_above_range"))
         sc_mic = (bw.get("sensor_check") or {}).get("mic") or {}
         rd.mic_channel_test_result   = sc_mic.get("result")
         rd.mic_channel_test_freq_hz  = sc_mic.get("freq_hz")
@@ -236,15 +238,16 @@ def gather_report_data(
             ch_when_iso = peak_when.get(ch_label)
             peak_date, peak_time = _split_iso_to_date_time(ch_when_iso)
             rd.channel_stats.append({
-                "name":          ch_label,
-                "ppv_ips":       ch.get("ppv_ips"),
-                "zc_freq_hz":    ch.get("zc_freq_hz"),
-                "time_of_peak_s": ch.get("time_of_peak_s"),
-                "peak_accel_g":  ch.get("peak_accel_g"),
-                "peak_disp_in":  ch.get("peak_disp_in"),
-                "sensor_check":  sc_ch.get("result"),
-                "peak_date":     peak_date,
-                "peak_time":     peak_time,
+                "name":               ch_label,
+                "ppv_ips":            ch.get("ppv_ips"),
+                "zc_freq_hz":         ch.get("zc_freq_hz"),
+                "zc_freq_above_range": bool(ch.get("zc_freq_above_range")),
+                "time_of_peak_s":     ch.get("time_of_peak_s"),
+                "peak_accel_g":       ch.get("peak_accel_g"),
+                "peak_disp_in":       ch.get("peak_disp_in"),
+                "sensor_check":       sc_ch.get("result"),
+                "peak_date":          peak_date,
+                "peak_time":          peak_time,
             })
 
         # MicL peak time (used in the mic block — "PSPL ... on DATE at TIME")
@@ -612,7 +615,8 @@ def _mic_rows(rd: ReportData) -> list[tuple[str, Optional[str]]]:
             line += f" at {rd.mic_pspl_time_s:.3f} sec."
         rows.append(("PSPL", line))
     if rd.mic_zc_freq_hz is not None:
-        rows.append(("ZC Freq", f"{rd.mic_zc_freq_hz:.0f} Hz"))
+        prefix = ">" if rd.mic_zc_freq_above_range else ""
+        rows.append(("ZC Freq", f"{prefix}{rd.mic_zc_freq_hz:.0f} Hz"))
     if rd.mic_channel_test_result:
         line = rd.mic_channel_test_result
         if rd.mic_channel_test_freq_hz is not None and rd.mic_channel_test_amp_mv is not None:
@@ -684,13 +688,17 @@ def _draw_stats_table(ax, rd: ReportData, rows_spec: list[tuple[str, str, str]])
     ch_lookup = {c["name"]: c for c in rd.channel_stats}
 
     def _cell(field, ch_name):
-        val = ch_lookup.get(ch_name, {}).get(field)
+        ch_rec = ch_lookup.get(ch_name, {})
+        val = ch_rec.get(field)
         if val is None:
             return "—"
         if isinstance(val, float):
-            # ZC Freq is integer-formatted in BW; everything else with 3 decimals
+            # ZC Freq is integer-formatted in BW; ">100 Hz" sentinel
+            # rendered as ">N" (val carries the threshold).  Everything
+            # else gets 3 decimals.
             if field == "zc_freq_hz":
-                return f"{val:.0f}"
+                prefix = ">" if ch_rec.get("zc_freq_above_range") else ""
+                return f"{prefix}{val:.0f}"
             return f"{val:.3f}"
         return str(val)