refactor(cli): simplify version-mismatch update preflight #36519

Summary

The fresh-launch version-mismatch path now carries a bespoke ~500-line animated terminal application plus renderer ownership handoff for a startup gap described as lasting up to roughly five seconds.

Evidence

The implementation arrived across:

• feat(cli): update preflight UI while replacing the background service #36448 / 1ccaca8: custom split-footer preflight
• fix(cli): hand update completion directly to the TUI #36455 / 56a7c06: coordinated per-cell completion transitions
• fix(cli): keep update preflight through TUI loading #36475 / e22e3b8: keep the preflight renderer alive and transfer it into the TUI

packages/cli/src/services/update-preflight.tsx now owns stage floors, timed transitions, spring motion, glow ramps, character cells, custom fades/sweeps, settlement races, renderer teardown, and renderer transfer. packages/tui/src/app.tsx accepts the transferred renderer and removes the preflight after first paint.

This is a large independent lifecycle and rendering surface for a rare transitional state. It also couples CLI service replacement to TUI renderer internals.

Direction

Prefer one startup ownership path:

• render a plain status through the normal TUI startup/loading surface, or
• keep the preflight to one stable status line and destroy it before ordinary TUI startup.

If renderer transfer is genuinely required elsewhere, first make it a small general lifecycle primitive rather than embedding it in update-specific animation code.

Acceptance

• Preserve clear feedback during version-mismatch replacement and a readable failure.
• Remove update-specific cell-transition/spring/rail machinery and artificial stage holds.
• Keep renderer ownership and teardown in one obvious place.
• Avoid coupling service replacement stages to a second miniature TUI.

Source

Daily V2 slop review: https://slack.com/archives/C0BE69AHCQP/p1783485085831699