TUI: terminal pet active animations fall back to idle before task state changes

Summary

Terminal pets are selected by a semantic app state (running, waiting, review, or failed), but their playback is currently governed by an animation timer rather than the lifetime of that state. As a result, the active animation can stop even though the task is still active.

!Before and after terminal pet lifecycle

Reproduction

1. Enable a built-in terminal pet.
2. Start a task that runs longer than one working-animation sequence.
3. Watch the pet while the task is still running.

Current behavior

• Built-in app-state animations repeat their active frames three times, then enter an appended idle tail indefinitely.
• A running pet notification expires after a fixed three minutes even if the turn is still active.
• Interrupting a turn does not explicitly clear the active pet notification.
• A completion animation uses a fixed stale-notification lifetime rather than reflecting the duration of the task that just completed.

The behavior comes from app_state_animation appending idle frames and setting loop_start to that idle tail, combined with a fixed RUNNING_LIFETIME in the ambient pet state.

Expected behavior

• The working animation loops for as long as the turn is active, with no arbitrary timeout.
• Waiting, blocked, and ready/review animations keep playing while their corresponding visible state remains active.
• Completion or failure replaces the working state immediately.
• Interruption clears the working state immediately.
• The post-task review animation lasts for the completed task's duration, capped at three minutes.
• Transient pointer animations such as hover and drag retain their existing one-shot behavior.

This should apply uniformly to built-in and custom terminal pets.

Environment

• Platform: Linux terminal
• Reproduced on current main at 78d4a563f9ecaf5c331bfa4ae7332885a1d9e2f6

Related

• #23272 tracks the analogous one-shot-to-idle behavior in the desktop pet.
• #28995 tracks desktop overlay state animations falling back to idle.
• #30268 requests configurable pet animation duration.
• #20863 requests richer custom pet animation/activity configuration.