Polish session takeover prompts and handoff notices

[Brian Krabach (bkrabach)]

Session takeover currently presents raw lock metadata and a plain confirmation prompt. Interactive chat now shows a Rich panel naming the current app and host, a styled confirmation, progress while the owner stops and saves, and a clear acquisition or failure notice. The yielding CLI also displays a matching handoff panel naming the requesting app.

Declining or failing takeover no longer repeats the raw lock error at startup. Script and JSON diagnostics retain their existing behavior, and ownership is still granted only by acquiring the real lock.

Validation:

• Full CLI suite: 2,365 passed, 45 skipped, 13 integration tests deselected, 1 expected failure. All 13 integration tests passed in a separate run.
• Real terminal checks at 80 and 42 columns: accepted takeover through the Foundation lock/request protocol, default decline, and an owner without release-request support.
• Changed handoff module/tests pass Ruff; diff whitespace checks pass.