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/setting.go

@@ -41,9 +41,9 @@ func init() {
 		AppVer = "dev"
 	}
 
-	// We can rely on log.CanColorStdout being set properly because modules/log/console_windows.go comes before modules/setting/setting.go lexicographically
+	// FIXME: the logger shouldn't be initialized here, the app entry should initialize the logger
 	// By default set this logger at Info - we'll change it later, but we need to start with something.
-	log.SetConsoleLogger(log.DEFAULT, "console", log.INFO)
+	log.SetupStderrLogger(log.DEFAULT, "console-stderr", log.INFO)
 }
 
 // IsRunUserMatchCurrentUser returns false if configured run user does not match