Add .env.example to Document Required Environment Variables

[ig-imanish]

Description

The repository currently doesn't include an .env.example file, making it difficult for new contributors to know which environment variables are required to run the project locally.

Adding an example environment file improves the onboarding experience and reduces setup errors.

Proposed Solution

Create an .env.example file in the project root containing all required environment variables with placeholder values.

Example:

DODO_API_KEY=your_dodo_api_key

Only include variable names and placeholder values—never commit secrets or production credentials.

Additionally:

• Keep .env.example updated whenever new environment variables are introduced.
• Add a note in the README instructing contributors to copy .env.example to .env before running the project.

Benefits

• Easier onboarding for new contributors
• Clear documentation of required configuration
• Prevents accidental sharing of secrets
• Reduces setup-related issues

Acceptance Criteria

• Add an .env.example file with all required environment variables
• Replace all sensitive values with placeholders
• Update the README with environment setup instructions
• Keep .env.example synchronized with future configuration changes