Packaging: simplify installation and startup

[zyang37]

Reduce friction for new users by making Vera easy to install and run with minimal setup.

The goal is to allow users to start the emulator and begin testing in just a few steps, without manually managing dependencies or containers.

Goals

1. Single command installation
   Users should be able to install Vera with a simple command (e.g., pip install vera or brew install vera).

2. Simple startup command
   After installation, users can start the emulator with: vera run aws