Extend commands to modify config

```
erica init mobilefuton
erica init http://127.0.0.1:5984/mobilefuton

erica init android http://127.0.0.1:5985/mobilefuton

erica set android http://127.0.0.1:5986/mobilefuton
```

Start by locating the existing `erica init` and `erica set` command entry points and tracing how they read or write configuration. Compare the requested local, CouchDB, Android, and `set` examples to determine the intended behavior and validation. Done means the commands modify configuration consistently for each shown form, with appropriate command-level tests if the project has them.

Written by the indexing model from the issue text.