quieten routine tab logging and harden the failure summary

Follow-ups from running the conversion against a live account.

Tab open/close bookkeeping moves from info to debug. It was 19 of the 33
records in a full run, so the six task outcomes that are the point of the
summary were outnumbered three to one by tab handles and query strings. The
"could not close" case stays at warning, a tab that will not close is a real
problem rather than bookkeeping.

The [FAIL] summary moves into log_utils.exception_summary, which takes the
first line, drops the "(Session info: ...)" fragment and caps the result. A
selenium exception embeds the whole msedgedriver stacktrace in str(), and the
cap means a pathological message cannot push a screenful of text into one
record. The cut marker is ASCII because this can land on a Windows console
whose encoding cannot represent an ellipsis.

The suppressed-library list was checked rather than guessed: with the root
logger wide open, a real browser session plus one ollama call produced records
from httpx, httpcore, urllib3 and selenium only, and nothing else. That set is
already pinned. Worth noting selenium alone emits 45 records for a single page
load, so without the pinning the debug mode this PR recommends for bug reports
would be unusable.

src/log_utils.py

@@ -7,6 +7,7 @@ before this runs, so import order does not matter.
 
 import logging
 import os
+import re
 import sys
 
 LEVEL_ENV_VAR = "REWARDS_FARMER_LOG_LEVEL"
@@ -21,6 +22,36 @@ DEFAULT_LEVEL = "INFO"
 # default would make the output noisier than what it replaces.
 NOISY_LIBRARIES = ("httpx", "httpcore", "urllib3", "selenium")
 
+# Longest a one-line exception summary may get before it is cut. Long enough
+# for any real selenium message, short enough that a pathological one cannot
+# push a whole screen of text into a single record.
+MAX_SUMMARY_LENGTH = 300
+
+_SESSION_INFO = re.compile(r"\s*\(Session info:[^)]*\)")
+
+
+def exception_summary(exc: BaseException) -> str:
+	"""One short line describing an exception, safe to put in a log record.
+
+	str() on a selenium exception is multi-line: the message, then a session
+	info line, then the whole msedgedriver stacktrace. Only the first line is
+	worth showing in a per-task summary, and the full detail is still attached
+	as a traceback when the level is debug.
+	"""
+	text = str(exc).strip()
+
+	if not text:
+		return ""
+
+	text = _SESSION_INFO.sub("", text.splitlines()[0]).strip()
+
+	if len(text) > MAX_SUMMARY_LENGTH:
+		# ASCII, because this can land on a Windows console whose encoding
+		# cannot represent an ellipsis character.
+		text = text[:MAX_SUMMARY_LENGTH - 3].rstrip() + "..."
+
+	return text
+
 # CRITICAL is the longest level name at 8 characters, so pad to that and the
 # message column stays aligned no matter what is being logged.
 LOG_FORMAT = "%(asctime)s %(levelname)-8s %(name)s: %(message)s"