fix: Make TEE Plugin available to launch agent & fix previous launch error

[HashWarlock]

Relates to:

Risks

Low, risks are removed by making sure default env variable WALLET_SECRET_SALT is undefined.

Background

Remove default salt in the .env.example file to remove launch agent errors with TEE Plugin. Add tee plugin back into agent startup file so users can launch a TEE agent with a character file.

What does this PR do?

• Remove agent launch errors that use TEE Plugin
• Adds logic for Agent to startup in a TEE Plugin with or without a simulator

What kind of change is this?

Bug fixes

Documentation changes needed?

My changes do not require a change to the project documentation.

Testing

Where should a reviewer start?

I created a short YouTube video to explain the steps.
https://youtu.be/RABERCv5FiA

Detailed testing steps

• Add the env variable WALLET_SECRET_SALT with a value in the character config file.

Example for env vars to test locally:
DSTACK_SIMULATOR_ENDPOINT=http://localhost:8090
WALLET_SECRET_SALT=secretSalt

• Build project pnpm build
• Launch the TEE Simulator to test locally

docker run --rm -p 8090:8090 phalanetwork/tappd-simulator:latest

• pnpm start