docs(changelog): Unreleased — FFT, USBM compliance chart, sensor self-check

Document the feat/fft-series3 work under Unreleased: Blastware-compatible
channel FFT, the USBM RI8507/OSMRE compliance chart on the event-report PDF,
the decoded sensor self-check strip + Frequency/Overswing sub-rows, and the
seismo_lab Inspector hex reader — plus the two report-panel fixes (tick
collision, header serial fit). Additive, no .h5/DB change or backfill.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01YDXjZCr4RqT2U3QvMDhgzf

CHANGELOG.md

@@ -4,6 +4,66 @@ All notable changes to seismo-relay are documented here.
 
 ---
 
+## Unreleased
+
+**Blastware Event/FFT-Report parity — the FFT, the USBM compliance chart, and
+the sensor self-check.** Three analyses Blastware derives from event data,
+reverse-engineered against BE12844 (MiniMate Plus) reports and reproduced in
+seismo-relay: the compliance chart and the sensor-check strip now render on
+the event-report PDF, and the FFT reproduces Blastware's FFT Report. All three
+are additive and read from data already on disk — the `.h5` samples and the
+retained raw BW binary — so there is **no `.h5`/DB change, no migration, and no
+backfill**: a report regenerated for an existing event simply gains the new
+panels.
+
+### Added
+- **Blastware-compatible channel FFT (`waveform_fft`).** Reproduces Blastware's
+  FFT Report: DC-removed, no window, zero-padded to 4096 (0.25 Hz bins at
+  1024 sps), single-sided `2/N` amplitude. Matches Blastware's dominant
+  frequency to the exact bin and the amplitude to report precision across all
+  28 channels of the 7-event BE12844 oracle set. `channel_spectrum()` /
+  `dominant_frequency()`; tests in `tests/test_waveform_fft.py`.
+
+- **USBM RI8507 / OSMRE compliance chart on the event-report PDF
+  (`sfm/compliance.py`).** The velocity-vs-frequency blasting-compliance
+  scatter Blastware draws in the upper-right of its Event Report: each channel's
+  significant cycles as `(frequency, peak velocity)` points (zero-crossing
+  method, so each channel's cloud tops out at its PPV) plotted against the
+  RI8507 Drywall (0.75 in/s) and plaster (0.50 in/s) limit curves, drawn
+  continuous (constant-displacement bounds meeting the plateaus — no vertical
+  steps). Sized and positioned to match a Blastware report, measured off the
+  reference PDF. A technical breakdown of the curve is in
+  `docs/ri8507_compliance_curve.md`.
+
+- **Sensor self-check waveforms decoded and drawn (`minimateplus.sensor_check`).**
+  The "Sensor Check" traces Blastware shows to the right of the waveform panel
+  live in the series-3 binary's trailing block as four length-prefixed records
+  (`0x3c`–`0x3f`) using the same delta-block codec as the main waveform:
+  Tran/Vert/Long geophone ring-downs (the transducer's damped impulse response —
+  resonant frequency + overswing/damping) and a MicL pulse train (the mic's
+  known-signal gain check). `gather_report_data` decodes them from the retained
+  BW binary at report time; the report renders them as a strip flush against the
+  waveform panel plus the **Sensor Check → Frequency / Overswing Ratio** sub-rows
+  in the stats table. Verified against the reports on all 7 oracle events (mic
+  zero-crossing frequency = 20.1 Hz exact; geophone ring-downs consistent
+  ~7.5 Hz with overswing ~3.5). Tests in `tests/test_sensor_check.py`.
+
+- **Inspector tab in `seismo_lab.py` — annotated hex reader for series-3
+  binaries (`minimateplus/binary_annotate.py`).** Tiles a raw Blastware file
+  into labeled spans (header / STRT / body record-chain / trailing metadata +
+  calibration + sensor-check records / footer) so a binary can be combed by eye.
+
+### Fixed
+- **Event-report waveform panel — stacked-lane y-tick collision.** The lanes
+  touch, so each lane's bottom `-1.0` overprinted the next lane's top `1.0` at
+  the shared boundary. Prune the extreme ticks so each lane shows clean interior
+  ticks only.
+- **Event-report header — serial+firmware line ran off the page.** The long
+  `BE##### V ##.##-#.## MiniMate Plus` string overflowed the right margin;
+  tighter right-column indent + BW's slightly smaller header size so it fits.
+
+---
+
 ## v0.30.0 — 2026-09-12
 
 **The series-4 correctness release** — the Thor / Micromate counterpart to