Multiple archive searcher

[rgaudin]

As highlighted by #229, Searcher's getResults() only yields result's entry path. while convenient for single-archive search, it prevents implementing multi-ZIM search as results would only be path strings from multiple ZIMs.

We should then implement multiple ZIM search properly by

• Binding addArche to Searcher (ref impl in Add searcher add archive #229)
• Change Searcher API so that results can be identified

[HelloWorld-25]

Hello! I am Nithish Balaguru, a Information Technology & Sophomore year student in MSEC , I'm passionate about open-source development and contributing to impactful projects. I have experience in C,Python, Java, web development & Working on the GSoC 2026 project, here’s an implementation for [Add multi-archive search support and identifiable search results] and I enjoy solving challenging problems through code. I am excited to contribute to GSoC 2026, learn from the community and help advance for Project Kiwix through meaningful contributions.