"gh aw edit" should be able to edit a "source managed" workflow


```
dsyme@DSYME-LAPDOG:~/Paket$ ../gh-aw/gh-aw edit repo-assist --schedule "hourly"
✗ cannot edit a source-managed workflow; update its source or pin, then run gh aw update
```

This is wrong - we should be able to locally edit a source managed workflow as updates from source merge in edits. 
 