fix(lib): cap a search reply at 150 files

A broad query against a big share was answered with every match, so one
search could hand the whole index to a stranger, and every such search
did it again. A reply now carries at most MAX_SEARCH_REPLY_FILES (150,
Nicotine+'s default), which is more sources than any searcher scrolls
through.

soulseek-rs-lib/src/client/mod.rs

@@ -146,6 +146,7 @@ fn build_search_response(
     }
     let entries: Vec<FileEntry> = matches
         .iter()
+        .take(crate::types::MAX_SEARCH_REPLY_FILES)
         .map(|f| FileEntry {
             name: &f.virtual_path,
             size: f.size,