Fix scroll position bugs and implement jump list navigation

[0xDAEF0F]

Summary

• Fix scroll position not being restored correctly when switching buffers
• Hide autocomplete panel when navigating with arrow keys or mouse clicks
• Hide autocomplete panel when switching buffers
• Implement jump list for Go to Definition navigation with back/forward arrows

Jump List Feature

Navigate back and forward through your code exploration history when using Go to Definition:

• Back/forward arrows in the breadcrumb toolbar (left side)
• Keyboard shortcuts: Ctrl+- (back) and Ctrl+Shift+- (forward)
• Works with both Cmd+Click and F12 Go to Definition
• Automatically reopens closed files when navigating back
• Deduplicates nearby positions (within 5 lines)

Test plan

• Open multiple files and switch between them - scroll position should be preserved
• Type to trigger autocomplete, then press arrow keys - panel should hide
• Type to trigger autocomplete, then switch buffers - panel should not appear in new buffer
• Use Cmd+Click or F12 to go to a definition - back arrow should enable
• Click back arrow or press Ctrl+- to return to previous position
• Click forward arrow or press Ctrl+Shift+- to go forward again
• Close a file, then navigate back to it - file should reopen at correct position