Keep the missing-weekday note honest about market holidays

A weekday with no published index is usually just a market holiday
(~10/yr), not a fault. The WARNING still earns its place as the guard
against inferring missing from an error code, but the comment should
not claim more than it can.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

app/services/sec_client.py

@@ -289,10 +289,11 @@ class SecClient:
         try:
             text = await self.get_text(url)
         except SecNotFoundError:
-            # Absent is normal on a weekend (SEC publishes business days only). On a
+            # Absent on a weekend is routine (SEC publishes business days only); on a
-            # weekday it is not: a SEC hiccup — or a rejection page misread as absent
+            # weekday it is either a market holiday or something worth a look — a SEC
-            # — would otherwise let the importer advance past real filings silently,
+            # hiccup, or a rejection page misread as absent, would otherwise let the
-            # so surface it at WARNING instead of hiding it in the info stream.
+            # importer advance past real filings silently. Log-level only, no alert:
+            # cheaper than carrying a holiday calendar just to stay quiet ~10 days/yr.
             logger.log(
                 logging.INFO if day.weekday() >= 5 else logging.WARNING,
                 "no daily index published for %s (%s)",