node info uses --ip instead of --rpc-url, inconsistent with other commands

## Problem

Every command uses `--rpc-url` for specifying a custom endpoint, but `node info` uses `--ip`:

```
platform node info --ip 127.0.0.1 # works
platform node info --rpc-url http://127.0.0.1:9650 # ignored, still requires --ip
```

This is confusing because `--rpc-url` is a global flag that works everywhere else (wallet, transfer, subnet, etc).

## Suggested Fix

- Accept `--rpc-url` as the primary way to specify the node (extract host from URL)
- Keep `--ip` as an alias for backward compatibility
- Default port to 9650 when only an IP is provided

## Environment
- platform-cli v1.0.1