Purpose

The goal of this PR is to add a script that starts up SAT connected to the paseo testnet.

Closes #94 Closes #95

Solution

./start-gateway.sh implemented to gather user input and run the docker compose command.
docker-compose.yaml added with changes to connect to testnet and remove dependency on the frequency container.
./stop-gateway.sh implemented to shutdown and optionally remove volumes.
ContentWatcherService is updated to poll the health endpoint for Ready before attempting to configure content-watcher.

Execute ./start-gateway.sh.
Verify that all containers start correctly by examining Docker Desktop logs.
Test SAT functionality.
Execute ./stop-gateway.sh and verify that the containers are stopped and optionally volumes are deleted.
Verify the contents of .env-saved

Content-watcher is updated to have a 2-hour (600) block rewind. This allows SAT to sync up with the current end of the chain quickly. However, it means that any posts more than 2 hours old will not show up. [A separate issue is in the works to update content-watcher so that it can sync further back, and still monitor the end of the chain and new posts]
Users will have to look up or know the Provider Id and Seed Phrase before running the startup script.
npm install is not necessary for running on Testnet, but it is needed in the backend to run npm run local:init when running a local node, as specified in the README.md. npm install is done inside the container, and the Docker volume is mapped to the host system, but the host will not see the volume until npm install writes the files locally, and the host files should be in sync with the docker files.