Provide issue/task comparison tool

[dmeehan1968]

It could be useful to compare two issue histories, but the UI doesn't really make this easy. Checkboxes could be provided on the issues list, but this also then needs to drill into which task to compare.

Assuming a prompt and the codebase were identical, this might provide a way to highlight differences in Junie operation, for example depending on LLM version, guidelines or MCP availability.

One could just open two browser windows and put the events/trajectories/steps views side by side.

[dmeehan1968]

Partially addressed in https://github.com/dmeehan1968/junie-explorer/releases/tag/v3.0.0