feat: decode waveform record timestamp, record type, and Peak Vector Sum

Confirmed 2026-04-01 against Blastware event report for BE11529 thump
event ("00:28:12 April 1, 2026", PVS 3.906 in/s).

models.py:
- Timestamp.from_waveform_record(): decode 9-byte format from 0C record
  bytes[0-8]: [day][sub_code][month][year:2BE][?][hour][min][sec]
- Timestamp: add hour/minute/second optional fields; __str__ includes
  time when available
- PeakValues: add peak_vector_sum field (confirmed fixed offset 87)

client.py:
- _decode_waveform_record_into: add timestamp decode from bytes[0:9]
- _extract_record_type: decode byte[1] (sub_code), not ASCII string
  search; 0x10 → "Waveform", histogram TBD
- _extract_peak_floats: add PVS from offset 87 (IEEE 754 BE float32)
  = √(T²+V²+L²) at max instantaneous vector moment

sfm/server.py:
- _serialise_timestamp: add hour/minute/second/day fields to JSON
- _serialise_peak_values: add peak_vector_sum to JSON

docs: update §7.7.5 and §8 with confirmed 9-byte timestamp layout,
PVS field, and byte[1] record type encoding; update command table;
close resolved open questions.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

minimateplus/client.py

@@ -394,25 +394,30 @@ def _decode_waveform_record_into(data: bytes, event: Event) -> None:
     The *data* argument is the raw record bytes returned by
     MiniMateProtocol.read_waveform_record() — i.e. data_rsp.data[11:11+0xD2].
 
-    Extracts:
-      - record_type: "Histogram" or "Waveform" (string search) 🔶
-      - peak_values: label-based float32 lookup (confirmed ✅)
-      - project_info: "Project:", "Client:", etc. string search ✅
-
-    Timestamp in the waveform record:
-      7-byte format: [0x09][year:2 BE][0x00][hour][minute][second]
-      Month and day come from a separate source (not yet fully mapped ❓).
-      For now we leave event.timestamp as None.
+    Extracts (all ✅ confirmed 2026-04-01 against Blastware event report):
+      - timestamp:    9-byte format at bytes [0:9]
+      - record_type:  sub_code at byte[1] (0x10 = "Waveform")
+      - peak_values:  label-based float32 at label+6 for Tran/Vert/Long/MicL
+      - peak_vector_sum: IEEE 754 BE float at offset 87
+      - project_info: "Project:", "Client:", etc. string search
 
     Modifies event in-place.
     """
+    # ── Timestamp ─────────────────────────────────────────────────────────────
+    # 9-byte format: [day][sub_code][month][year:2 BE][unknown][hour][min][sec]
+    try:
+        event.timestamp = Timestamp.from_waveform_record(data)
+    except Exception as exc:
+        log.warning("waveform record timestamp decode failed: %s", exc)
+
     # ── Record type ───────────────────────────────────────────────────────────
+    # Decoded from byte[1] (sub_code), not from ASCII string search
     try:
         event.record_type = _extract_record_type(data)
     except Exception as exc:
         log.warning("waveform record type decode failed: %s", exc)
 
-    # ── Peak values ───────────────────────────────────────────────────────────
+    # ── Peak values (per-channel PPV + Peak Vector Sum) ───────────────────────
     try:
         peak_values = _extract_peak_floats(data)
         if peak_values:
@@ -431,14 +436,24 @@ def _decode_waveform_record_into(data: bytes, event: Event) -> None:
 
 def _extract_record_type(data: bytes) -> Optional[str]:
     """
-    Search the waveform record for a record-type indicator string.
+    Decode the recording mode from byte[1] of the 210-byte waveform record.
 
-    Confirmed types from 3-31-26 capture: "Histogram", "Waveform".
-    Returns the first match, or None if neither is found.
+    Byte[1] is the sub-record code that immediately follows the day byte in the
+    9-byte timestamp header at the start of each waveform record:
+      [day:1] [sub_code:1] [month:1] [year:2 BE] ...
+
+    Confirmed codes (✅ 2026-04-01):
+      0x10 → "Waveform"   (continuous / single-shot mode)
+
+    Histogram mode code is not yet confirmed — a histogram event must be
+    captured with debug=true to identify it.  Returns None for unknown codes.
     """
-    for rtype in (b"Histogram", b"Waveform"):
-        if data.find(rtype) >= 0:
-            return rtype.decode()
+    if len(data) < 2:
+        return None
+    code = data[1]
+    if code == 0x10:
+        return "Waveform"
+    # TODO: add histogram sub_code once a histogram event is captured with debug=true
     return None
 
 
@@ -486,11 +501,23 @@ def _extract_peak_floats(data: bytes) -> Optional[PeakValues]:
     if not vals:
         return None
 
+    # ── Peak Vector Sum — fixed offset 87 (✅ confirmed 2026-04-01) ───────────
+    # = √(Tran² + Vert² + Long²) at the sample instant of maximum combined geo
+    # motion, NOT the vector sum of the three per-channel peak values (which may
+    # occur at different times).  Matches Blastware "Peak Vector Sum" exactly.
+    pvs: Optional[float] = None
+    if len(data) > 91:
+        try:
+            pvs = struct.unpack_from(">f", data, 87)[0]
+        except struct.error:
+            pass
+
     return PeakValues(
         tran=vals.get("tran"),
         vert=vals.get("vert"),
         long=vals.get("long_"),
         micl=vals.get("micl"),
+        peak_vector_sum=pvs,
     )