feat(opencode): improve pasted summary toggling and styling

[haddoumounir]

Issue for this PR

Closes #8501

Type of change

• Bug fix
• New feature
• Refactor / code improvement
• Documentation

What does this PR do?

I improved pasted summary behavior in the TUI prompt so pasted content is easier to inspect and edit before submit.

Main changes:

• I added expand/collapse behavior for pasted summaries directly from the prompt.
• I improved pasted summary rendering/styling so multiple pasted blocks are easier to distinguish.
• I improved submit time expansion so full pasted text is correctly included when sending.
• I kept related test hardening updates to reduce flaky behavior in status popover interactions and runner cancellation paths.

Why this works:

• Prompt state and extmark updates stay in sync when toggling summaries.
• Expanded/collapsed text is handled consistently before submit.
• Related timing sensitive paths now have stronger test coverage.

How did you verify your code works?

• I manually validated paste summary toggle behavior in the TUI prompt.
• I updated related tests for status popover and runner cancellation paths.
• I validated the branch is clean and focused into two commits.

Screenshots / recordings

I added a short before/after video showing paste summary toggle behavior and submit behavior.

demo.mp4

Checklist

• I have tested my changes locally
• I have not included unrelated changes in this PR

[github-actions]

The following comment was made by an LLM, it may be inaccurate:

Related PRs Found:

Based on my search, here are potentially related PRs addressing similar pasted summary features:

1. feat(tui): Allow to expand pasted text (AKA "pasted summary") - feat(tui): Allow to expand pasted text (AKA "pasted summary") #8496

   • Directly related: Addresses expanding pasted text in the TUI

2. feat(tui): make pasted summaries expandable/collapsible in prompt - feat(tui): make pasted summaries expandable/collapsible in prompt #17248

   • Directly related: Adds expand/collapse functionality for pasted summaries in the prompt

3. feat(app): collapse large pasted input blocks - feat(app): collapse large pasted input blocks #15411

   • Related: Handles collapsing large pasted input blocks

These PRs all address expand/collapse behavior for pasted content in the TUI prompt, which is the core feature of PR #21205. You may want to verify that #21205 is not duplicating work from these previous PRs, or if it's a refinement/improvement on top of them.