[lana-20]

Fixes #328.

283 made session end say what it discards, but only in its text. Every client dropped the answer, so a recording was lost at exit 0.

What changes

• app_session and app_shutdown answer discarded. The list also names a running trace and a speech listen. A trace was lost at session end with no word.
• Each client's quit warns: Python and JavaScript a MobiumWarning, Go the standard logger, Java the dev.mobium logger, .NET standard error.
• Python warns every time. Its default shows a warning once per place, so three lost recordings warned once. -W ignore still silences it, and the warning points at the caller's line.
• A client that exits without quit, kill -9 included, has the pipe say it on standard error.
• A recording and a trace leave audio's lost-capture note (280). A later status or stop names the cause instead of "nothing is recording": another client's quit, daemon stop, a driver switch, a shutdown.

Measured

With a running recording: all five clients on the Android 15 emulator; Python, exit without quit and a trace on the iOS 26.5 simulator. pytest shows the warning in its summary. With the recording stopped first, nothing is said.

record, trace, files, clients and test-runner pass on Android; trace and audio-sim on iOS.

Not settled here

• A speech listen is covered by a test alone: TalkBack on this emulator does not log at VERBOSE.
• A client's start() reuses a session the CLI opened, and its quit ends it, so mobium record cannot film a client's run. It now warns, and the CLI's stop names why.
• mobium test over a running recording kept it, 1 run. The earlier lead did not reproduce.
• audio.sh fails 2 of 3 on main and on this branch alike, on a tone split by a short dropout. That is not this change.