A failed record press no longer blocks the next one (#315)

[Skeyelab]

Closes #315 (blocker from the whole-app review).

Before: startTake created the next Take folder on a copy of the Show and stored the Show only at the end. If anything after the folder failed (TakeSession, a Stem, the metadata), the next press got the same Take number, found the folder, and threw "file exists" until a relaunch or End Show. A Drive that failed at the press blocked recording outright, and a failure after the Drive was opened never let it go.

Now (Recorder.openTake, one attempt that undoes itself):

• A failed press removes only the Take folders it created (never one that was already there) and doesn't use up the Take number. The next press records Take 01.
• A Show created by that press stays open, so a retry doesn't make "… Show 2".
• If a Drive was in the press and it fails, the press retries on the Device alone; the Drive chip shows the problem. A Device that fails too throws its own error.
• The Drive access is let go exactly once on every path.

Tests, written first (FailedPressTests):

• a failed press (a Stem that can't be made) and then a working one records Take 01, with no leftover folder;
• a Drive whose folder can't be created still records to the Device;
• a failed press never deletes a Take folder that was already on disk. This test caught a bug in my first version, which removed the folder by name.

./scripts/verify.sh passes (431 tests). Not checked on a device (a full Device or a read-only Drive at the press).

https://claude.ai/code/session_01S6amVoNeB4GahnMMe79dZ6