v0.8.68 UX: default TUI presentation is too busy; compact mode should be standard

[Hmbown]

Bug

The default TUI presentation is too busy. During normal work it exposes too much low-level activity at once, changes too quickly, and makes the app feel chaotic even when the underlying work is healthy.

This should be treated as a 0.8.68 UX bug, not a new feature request: the default experience should feel calm, compact, readable, and deliberate. Detailed activity should still exist, but it should be opt-in.

Intended default

• Main timeline defaults to high-signal summary events, not every file/tool/detail.
• Tool calls collapse into stable progress rows such as current action, count, elapsed state, and result.
• Sub-agents show compact rows by default: role/name, model/route, current action, status/progress, and a concise completion summary.
• Workflow runs show phases/queues/agents at a readable pace instead of streaming every internal transition.
• Busy animations and rapidly changing text are throttled/coalesced so the screen feels slower and easier to parse.
• Modals and side panels avoid dense walls of copy unless the user explicitly opens details.
• Verbose mode restores the full detailed stream for debugging, including file reads, tool names, raw activity, and expanded traces.

Acceptance criteria

• There is a global compact/default presentation policy used across main chat, tools, workflows, sub-agents, fleet/setup surfaces, and detail panels.
• Default mode hides or coalesces repeated file/tool/read/progress spam while keeping enough signal to understand what is happening.
• Expanded/detail views and verbose mode expose the full activity without freezing or flooding the main surface.
• Activity updates are paced/throttled so the TUI does not visually churn under active fan-out or workflow runs.
• Existing power-user/debug detail remains accessible through an explicit verbose toggle or expanded inspection path.

Related: #4094, #3987, #4014

[Hmbown]

Cutover checklist companion created: #4112 tracks the remaining default-transcript copy polish items: read/search verb mismatch, completed reasoning disclosure, Tasks/Activity naming, duplicate delegate/unknown-child wording, and context/mode/setup hint duplication.