label each side in file diff view

[FindHao]

maybe we can just add a lable in the final parsed trace file name.

[FindHao]

Essentially, I'm imagining a scenario where we have two text boxes where users can type their own labels. The shareable URL would then include this label information, ensuring that when others open the URL, the labels are already pre-populated.

[hesam-oxe]

I can implement this. The approach is straightforward:

• Add two text inputs for left/right labels in the diff view
• Persist labels in the shareable URL as query params
• Pre-populate labels when loading from URL

Already familiar with the codebase from PR #405.

/assign