Read the source badge under the name the server writes (V-662)

scripts/usage-run.py read the redirect parameter "src". cmd/mavweb/chat.go
writes it as "s". So Source came back empty on all 140 turns of both
fortnight runs, and every finding in those two docs is read off the reply
wording instead of off the badge.

Re-run confirms the column now arrives: 68 of 140 turns name a source.
The two homelab misses are now direct evidence rather than inference.
"какая скорость у меня сейчас?" is claimed by weather and
"хватает ли места под новые бэкапы?" by feeds.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_013ptwopxyo3Z2kwFckHkLvN

scripts/usage-run.py

@@ -54,7 +54,11 @@ def turn(text):
         q = urllib.parse.parse_qs(urllib.parse.urlparse(loc).query)
         return {
             "reply": q.get("r", [""])[0],
-            "source": q.get("src", q.get("source", [""]))[0],
+            # "s", not "src". cmd/mavweb/chat.go writes the badge under that
+            # name, and reading the wrong one cost both fortnight runs their
+            # source column: every finding in those docs is inferred from the
+            # reply wording instead.
+            "source": q.get("s", [""])[0],
             "trace": q.get("t", [""])[0],
             "secs": dt,
         }