fix(import): derive record_type from filename suffix instead of hardcoding "Waveform"

The BW ACH ingest path was inserting every event with
record_type="Waveform" regardless of the actual type because
read_blastware_file() had `ev.record_type = "Waveform"` hardcoded, and
the live watcher-forward path parses files from a tmp path (suffix
".bw") that doesn't carry the original extension.

V10.72+ MiniMate Plus firmware encodes the event type as the last
character of the AB0T extension scheme (H=Histogram, W=Waveform,
M=Manual, E=Event, C=Combo).  This change:

  1. Adds derive_record_type_from_filename() public helper in
     minimateplus/event_file_io.py
  2. Uses it inside read_blastware_file() so direct callers (the
     --dry-run path of scripts/import_bw.py, tests, ad-hoc scripts)
     get correct types automatically
  3. Overrides ev.record_type in WaveformStore.save_imported_bw()
     using the ORIGINAL filename (source_path.name) — required
     because the parser sees only the tmp file

Old S338 firmware (3-char extensions ending in `0`) and any
unrecognized suffix fall back to "Waveform".

Existing DB rows ingested before this fix are stuck with
record_type="Waveform" — a one-off SQL backfill would fix them
retroactively if desired.  Terra-view's event modal also derives
client-side from the filename, so the UI already shows the correct
type for old events even without the backfill.

Version bumped to 0.16.1 in pyproject.toml, event_file_io.py
TOOL_VERSION, sfm/server.py FastAPI version, and CHANGELOG.md.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

sfm/server.py

@@ -86,7 +86,7 @@ app = FastAPI(
         "Implements the minimateplus RS-232 protocol library.\n"
         "Proxied by terra-view at /api/sfm/*."
     ),
-    version="0.16.0",
+    version="0.16.1",
 )
 
 # Allow requests from the waveform viewer opened as a local file (file://)