Stopped new-session and session-switch UI paths from detaching active loader/render components without running their disposal hooks.
Added container and loader coverage for disposing children before destructive transcript/status replacement.
Fixes#4686
- Added ChatBlock and ChatBlockHost with mount, finish, and dispose lifecycle callbacks.
- Added InteractiveModeContext.present and resetTranscript APIs and used them to mount/repaint blocks.
- Reworked controller rendering paths to emit command, event, extension, and selector outputs via ctx.present.
- Implemented component and container dispose hooks in tui so loaders and child blocks cleanup timers/effects.
roboomp