tui: improve aggregated waiting-agent status

[andrei-hasna]

Summary:

• replace opaque live wait UUID status with cached agent names and UUID fallback
• aggregate concurrent waits with bounded, sanitized activity and elapsed time
• preserve newer base statuses while the wait overlay is active and restore after the final wait
• add deterministic state snapshots plus a rendered multiline TUI snapshot

Verification:

• focused collab_wait tests: 9 passed
• official codex-tui package gate: 3357 passed, 4 skipped
• scoped Clippy fix/lint: passed without code warnings
• formatting, diff check, and pending snapshot check: passed
• staged and pre-push redacted secret scans: 0 findings
• independent post-fix adversarial review: approved with no P0-P3 findings

Residual risk:

• replayed in-progress items do not carry their original start timestamp, so replay age begins at receipt time
• targetless app-server v2 waits show generic agent text plus elapsed time because receiver identity metadata is unavailable

Todos: OPE2-00069 / 98e46b35-d8a8-47fa-a33b-3d5c0cc83c75