fix: make Collapse All button collapse all expandable elements in timeline

[everpcpc]

Summary

The "Collapse All" button in the timeline view was not working properly — it only collapsed tool calls but ignored diffs, command outputs, expanded commands, and thinking blocks.

This fix makes the button collapse all expandable elements:

• Inline diffs (via diff collapse trigger)
• Tool call expansions
• Command sections and expanded outputs in agent responses
• Thinking blocks

Changes:

• TimelineView.tsx: "Collapse All" button now triggers both diff and tool collapse. AgentResponse listens to the tool collapse context to collapse showCommands, expandedOutputs, and expandedCommands.
• ThinkingMessage.tsx: Added module-level collapse hook (same pattern as ToolCallMessage and InlineDiffViewer) so thinking blocks respond to the collapse-all trigger.

Tests

• Unit Test
• Logic Test
• Benchmark Test
• No Test - UI behavior change verified by type-checking; visual verification needed

Type of change

• Bug Fix (non-breaking change which fixes an issue)
• New Feature (non-breaking change which adds functionality)
• Breaking Change (fix or feature that could cause existing functionality not to work as expected)
• Documentation Update
• Refactoring
• Performance Improvement
• Other (please describe):