Add Call Tree timeline rendering

[jaehong-kim]

Summary

This PR adds timeline rendering to the Call Tree view. The previous execution percentage column is replaced with a timeline-style bar that shows each call stack row on its transaction time axis.

Changes

• Added Call Tree timeline bar rendering.
• Added async subtree axis calculation so async work remains visible even when it starts after the parent/root time window.
• Added parallel sibling detection and visual markers for overlapping execution.
• Extracted timeline geometry logic into timeline.ts.
• Added unit tests for timeline axis and parallel group calculation.
• Fixed Call Tree column refresh so timeline renderers update when transaction data changes.
• Kept Call Tree response typing aligned with the current backend call stack fields.

Validation

• Ran timeline.test.ts
• Result: 10 tests passed