fix: redirect early CLI console logger to stderr (#37507)

When running `gitea dump` with output routed to stdout (--file -),
deprecation warnings from loadAvatarsFrom were written to stdout,
corrupting the archive stream.

Root cause: PrepareConsoleLoggerLevel (called in app.Before) sets up a
console logger via SetConsoleLogger, which used WriterConsoleOption{}
defaulting Stderr to false (i.e. stdout). This logger is installed
before the dump subcommand can redirect logging to stderr in runDump.

Fix: use WriterConsoleOption{Stderr: true} in SetConsoleLogger so all
early CLI diagnostic output goes to stderr from the start. This is
correct for all subcommands — diagnostic/log output should never pollute
stdout.

---------

Signed-off-by: wxiaoguang <wxiaoguang@gmail.com>
Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>
Co-authored-by: Nicolas <bircni@icloud.com>

modules/setting/log.go

@@ -256,7 +256,7 @@ func initLoggerByName(manager *log.LoggerManager, rootCfg ConfigProvider, logger
 }
 
 func InitSQLLoggersForCli(level log.Level) {
-	log.SetConsoleLogger("xorm", "console", level)
+	log.SetupStderrLogger("xorm", "console-stderr", level)
 }
 
 func IsAccessLogEnabled() bool {