fix(review): bound TUISink.Wait, join the pump, surface drops (crew findings)

The live full-crew review of this branch (approve-path run, 3/3 reviewers succeeded through the hardened sink) returned three findings:

• Wait() blocked unconditionally on done, so the deferred teardown wait could still hang forever if Bubble Tea never returns from Run even after Kill — the wedge class survived at command exit. Wait now escalates: one grace period, Kill, one more grace, then abandons the goroutine. This also fixes the pre-existing early-error-path hang where nothing ever quit a healthy TUI before the deferred Wait.
• pumpDone was created and closed but never joined; Wait now joins the pump whenever the program actually exited.
• The dropped counter was invisible in production; PostRunComplete now debug-logs a non-zero count — the first diagnostic a future wedge investigation needs.

Pinned by a stubbornProgram fake whose Run never returns even after Kill: Wait must return within the bounded escalation.