Replace strings.Split with the lazy strings.SplitSeq iterator (Go 1.23+)
in loops that only range over the tokens, avoiding the intermediate
slice allocation. The yielded substrings are identical to Split, so
behavior is unchanged. Applies the suggestion from #5599 to its three
sites (CIDR parsing, WebDAV hidden-path, overlay path checks) and
extends it to two more split-and-iterate loops in the server compression
negotiator and MCP config-options builder for consistency. The slice
returning splitPath helper is intentionally left on strings.Split.
