Webapp: evidence pack date range, US month labels, hardware gap rows

Evidence pack takes ?from=&to= (inclusive, Eastern time) with From/To
pickers and quick ranges; ZIP is named ENT-056_<site>_<from>_to_<to>.
Month keys show as 'September 2026'. Hardware gap rows on the to-do
use the shared one-line grid with chips for the missing pack or BIOS.

webapp/services/blancco_evidence.py

@@ -182,16 +182,47 @@ def evidence_name(month: str, site: str | None = None) -> str:
     return f"ENT-056_{site_slug(site)}_{month}"
 
 
-def build_evidence_zip(month: str, fileobj) -> int:
-    """Write the evidence pack for `month` into fileobj; return report count."""
-    start, end = month_bounds(month)
+def evidence_range_name(first, last, site: str | None = None) -> str:
+    """File names stay year-first so they sort; the pages show US dates."""
+    return f"ENT-056_{site_slug(site)}_{first.isoformat()}_to_{last.isoformat()}"
+
+
+def day_bounds(first, last):
+    """date, date -> start of `first` and of the day after `last`, in the
+    site's display timezone (America/New_York): a whole-day range."""
+    from datetime import timedelta
+    start = datetime(first.year, first.month, first.day, tzinfo=_tz())
+    nxt = last + timedelta(days=1)
+    return start, datetime(nxt.year, nxt.month, nxt.day, tzinfo=_tz())
+
+
+def us_date(d) -> str:
+    """10/14/2026: the date format the site reads."""
+    return f"{d.month:02d}/{d.day:02d}/{d.year:04d}"
+
+
+def range_label(first, last) -> str:
+    return f"{us_date(first)} to {us_date(last)}"
+
+
+def build_evidence_zip(month, fileobj, first=None, last=None) -> int:
+    """Write an evidence pack into fileobj; return the report count. Either a
+    calendar month ('2026-09', the monthly pack) or a day range first..last
+    (dates, inclusive, Eastern time)."""
+    if first and last:
+        start, end = day_bounds(first, last)
+        stem = evidence_range_name(first, last)
+        period = range_label(first, last)
+    else:
+        start, end = month_bounds(month)
+        stem = evidence_name(month)
+        period = month
     reports = collect(start, end)
     state = load_state()
-    stem = evidence_name(month)
     with zipfile.ZipFile(fileobj, "w", zipfile.ZIP_DEFLATED) as zf:
         zf.writestr(f"{stem}/summary.csv", summary_csv(reports, state))
         zf.writestr(f"{stem}/README.txt", (
-            f"Blancco erasure evidence, {config.BLANCCO_SITE}, {month} ({config.DISPLAY_TZ})\n"
+            f"Blancco erasure evidence, {config.BLANCCO_SITE}, {period} ({config.DISPLAY_TZ})\n"
             f"{len(reports)} report(s). summary.csv has one row per erased drive,\n"
             "with failure_reason for failed wipes and cloud_upload as recorded by\n"
             "the PXE server. Certificates of record are in the Blancco Management\n"