Improve network naming consistency

1.
Runtime.zig -> Network.zig (especially since most places imported it as
`const Network = @import("Runtime.zig")`

2.
const net_http = @import(...) -> const http = @import(...)

src/Config.zig

@@ -34,7 +34,6 @@ pub const RunMode = enum {
     mcp,
 };
 
-pub const MAX_LISTENERS = 16;
 pub const CDP_MAX_HTTP_REQUEST_SIZE = 4096;
 
 // max message size