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>

sfm/server.py

@@ -83,11 +83,14 @@ def _serialise_timestamp(ts: Optional[Timestamp]) -> Optional[dict]:
     if ts is None:
         return None
     return {
-        "year": ts.year,
-        "month": ts.month,
-        "day": ts.day,
+        "year":      ts.year,
+        "month":     ts.month,
+        "day":       ts.day,
+        "hour":      ts.hour,
+        "minute":    ts.minute,
+        "second":    ts.second,
         "clock_set": ts.clock_set,
-        "display": str(ts),
+        "display":   str(ts),
     }
 
 
@@ -95,10 +98,11 @@ def _serialise_peak_values(pv: Optional[PeakValues]) -> Optional[dict]:
     if pv is None:
         return None
     return {
-        "tran_in_s": pv.tran,
-        "vert_in_s": pv.vert,
-        "long_in_s": pv.long,
-        "micl_psi":  pv.micl,
+        "tran_in_s":       pv.tran,
+        "vert_in_s":       pv.vert,
+        "long_in_s":       pv.long,
+        "micl_psi":        pv.micl,
+        "peak_vector_sum": pv.peak_vector_sum,
     }