fix ice_stocks XLS date parsing: handle 'Feb 20, 2026' format

ICE changed the daily stocks XLS header from 'As of: 1/30/2026' to
'As of: Feb 20, 2026  1:35:39PM'. Expand _build_canonical_csv_from_xls
to try multiple strptime formats (%m/%d/%Y, %b %d, %Y, etc.) on both
single-token and three-token date candidates.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

extract/ice_stocks/src/ice_stocks/execute.py

@@ -185,16 +185,33 @@ def _build_canonical_csv_from_xls(xls_bytes: bytes) -> bytes:
     """
     rows = xls_to_rows(xls_bytes)
 
-    # Extract report date from row 2, cell 0 (e.g. "As of: 1/30/2026")
+    # Extract report date from row 2, cell 0
+    # Formats seen: "As of: 1/30/2026", "As of: Feb 20, 2026  1:35:39PM"
     header_cell = str(rows[2][0]) if len(rows) > 2 else ""
     report_date = ""
     if "as of" in header_cell.lower():
-        date_part = header_cell.lower().replace("as of:", "").replace("as of", "").strip()
-        try:
-            dt = datetime.strptime(date_part.split()[0], "%m/%d/%Y")
-            report_date = dt.strftime("%Y-%m-%d")
-        except ValueError:
-            pass
+        # Strip prefix, preserve original case for month name parsing
+        after = header_cell.strip()
+        for prefix in ("As of:", "As Of:", "as of:", "As of", "As Of", "as of"):
+            if after.lower().startswith(prefix.lower()):
+                after = after[len(prefix):].strip()
+                break
+        tokens = after.split()
+        # Try "M/D/YYYY" (single token) then "Mon DD, YYYY" (three tokens)
+        candidates = [tokens[0]] if tokens else []
+        if len(tokens) >= 3:
+            candidates.append(" ".join(tokens[:3]))
+        for candidate in candidates:
+            candidate = candidate.rstrip(",")
+            for fmt in ("%m/%d/%Y", "%b %d, %Y", "%b %d %Y", "%B %d, %Y", "%B %d %Y"):
+                try:
+                    dt = datetime.strptime(candidate, fmt)
+                    report_date = dt.strftime("%Y-%m-%d")
+                    break
+                except ValueError:
+                    pass
+            if report_date:
+                break
 
     if not report_date:
         logger.warning(f"Could not parse report date from XLS header: {header_cell!r}")