Play Framework

feat(launcher): name system.out as console output and the log4j2 config (PF-176)

playStart, playRestart and the bundle launcher announced logs/system.out
as "output is redirected to", the only log location the framework ever
named, so operators read it as the application log. It holds console
output only. An app's log4j2 file appender writes the application log to
a path set inside the config that application.log.path names, and
playStart truncates system.out on every boot, so it is also the
shorter-lived copy.

The launcher cannot print the real log path: application.log.path is a
classpath resource name for the log4j2 config, and the appender's
fileName lives inside that XML, which the Gradle JVM cannot read back.
All three sites now print:

  ~ console output (stdout/stderr) -> <app>/logs/system.out
  ~ application logging follows <application.log.path>

or "the default log4j2 configuration (application.log.path is unset)"
when the key is absent. The Gradle tasks resolve the key through the
existing confValue(), so a %<id>. entry wins for the active play id, as
it already does for javaagent.path and jvm.memory. bundle-play.sh gains
conf_log_path, an awk lookup with the same rules, against the bundle's
play id (prod unless --%<id> is given).

OutputBannerTest runs playStart and playRestart through TestKit with a
%prod. value, the bare key and the key unset; BundleLauncherTest does the
same for ./play start. All six fail against the old wording. Verified
against a scaffolded app: the named config is the one writing
logs/application.log under play start, play restart and a play bundle.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>