promptfoo

Meaht to say `promptfoo view`

I'd like to be able to control this as something other than 15500.  Is there a good way?

Figured it out by reading the code:

```
 export API_PORT=3000
```

You can also use the `-p` or `--port` flags

also, to view all the options for any given command, you can do `promptfoo <command> -h`. e.g. `promptfoo view -h` would show:
```
Usage: promptfoo view [options] [directory]

Start browser UI

Options:
  -p, --port <number>             Port number (default: "15500")
  -y, --yes                       Skip confirmation and auto-open the URL
  -n, --no                        Skip confirmation and do not open the URL
  --filter-description <pattern>  Filter evals by description using a regex pattern
  --env-file, --env-path <path>   Path to .env file
  -v, --verbose                   Show debug logs (default: false)
  -h, --help                      display help for command
```