feat: add environment configuration and websocket session management

[raphaelvserafim]

• Introduced envs.ts for environment variable management.
• Implemented WebSocketSessionManager for handling websocket connections.
• Added function handlers for weather and Calendly scheduling.
• Updated server to utilize new environment configurations and session management.
• Removed legacy session management code.

[tylerclark]

@raphaelvserafim I saw your file on Calendly. My attempts to run that endpoint ended with:

{
    "title": "Resource Not Found",
    "message": "The requested path does not exist"
}