fix: eliminate UI flicker during task cancellation

[daniel-lxs]

Fixes the jarring UI flicker that occurs when cancelling a task.

Problem

When cancelling a task, Task.dispose() caused the UI to briefly navigate to the home view before returning to the task, creating a jarring user experience.

Root Cause

The issue was in ClineProvider.createTaskWithHistoryItem() which always called removeClineFromStack() first, causing the task stack to be temporarily empty and triggering the home view.

Solution

• Detection Logic: Added check for currentTask taskId === historyItem.id to identify task rehydration
• In-Place Replacement: When rehydrating the current task, replace it directly in the stack instead of removing first
• Event Cleanup: Properly clean up old event listeners and set up new ones
• Backward Compatibility: Normal task creation flow unchanged

Changes

• Modified ClineProvider.createTaskWithHistoryItem() to detect rehydration scenarios
• Implemented flicker-free in-place task replacement
• Added comprehensive unit tests in ClineProvider.flicker-free-cancel.spec.ts

Testing

• ✅ All existing tests pass (32 passed, 4 skipped)
• ✅ New flicker-free cancel tests pass (4/4)
• ✅ Type checking passes
• ✅ Linting passes

User Experience

Before: Cancel → Home flicker → Task view
After: Cancel → Seamless task rehydration

[roomote]

Code Review Complete ✅

No issues found. The implementation correctly addresses the UI flicker during task cancellation through in-place task replacement. Event listeners are properly managed, and comprehensive tests verify all scenarios.

Previous Reviews

• fcb06c4: Review #1

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