support `post-init` command hook

### Is this feature request related to a new or existing Amplify category?

_No response_

### Is this related to another service?

_No response_

### Describe the feature you'd like to request

I would like to execute a script after running `amplify init` in the event I want to run some logic after pulling the project from git and running `amplify init`

https://docs.amplify.aws/cli/project/command-hooks/#how-to-name-command-hook-scripts

### Describe the solution you'd like

see above

### Describe alternatives you've considered

using `post-pull`

### Additional context

_No response_

### Is this something that you'd be interested in working on?

- [ ] 👋 I may be able to implement this feature request

### Would this feature include a breaking change?

- [ ] ⚠️ This feature might incur a breaking change

Start with the command-hooks documentation linked in the issue and compare the requested post-init hook with the existing post-pull alternative. Trace how hooks are named and invoked around amplify init, then verify that a post-init script runs after amplify init completes without changing the existing hook behavior.

Written by the indexing model from the issue text.