feat(db): zip recent events' waveform files

sfm/db_snapshot.py

@@ -6,6 +6,7 @@ unit-testable without HTTP.
 """
 from __future__ import annotations
 import sqlite3
+import zipfile
 from pathlib import Path
 
 
@@ -22,3 +23,28 @@ def snapshot_db(src_path: Path, dest_path: Path) -> Path:
         src.close()
         dest.close()
     return Path(dest_path)
+
+
+def build_recent_waveforms_zip(db, store, n: int, dest_path: Path) -> dict:
+    """Zip every on-disk file (event file + .h5/.a5.pkl/.sfm.json siblings) for
+    the n most-recent events, arcname '<serial>/<filename>'. Events with no
+    resolvable files on disk are skipped. Returns {'events': int, 'files': int}."""
+    rows = db.query_events(limit=n, offset=0)
+    events = 0
+    files = 0
+    with zipfile.ZipFile(dest_path, "w", compression=zipfile.ZIP_DEFLATED) as zf:
+        for row in rows:
+            serial = row.get("serial")
+            fn = row.get("blastware_filename")
+            if not serial or not fn:
+                continue
+            serial_dir = store.root / serial
+            matched = sorted(serial_dir.glob(f"{fn}*")) if serial_dir.is_dir() else []
+            matched = [p for p in matched if p.is_file()]
+            if not matched:
+                continue
+            events += 1
+            for p in matched:
+                zf.write(p, arcname=f"{serial}/{p.name}")
+                files += 1
+    return {"events": events, "files": files}