Refactor handlers and introduce API wrapper

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• Updated Handler struct to include an API wrapper for better abstraction.
• Added middleware for JSON error handling.
• Refactored Operators and Places handlers to utilize the new API wrapper.
• Simplified Snapshot and Stream handlers to use the API wrapper for upstream requests.
• Removed deprecated token handling logic from handlers.
• Introduced centralized models for accounts, confirmations, cameras, places, and finances.
• Created a new upstream request handling mechanism for better error management.
• Implemented token refresh logic with a dedicated auth package.
• Added constants for API host and user agent.
• Enhanced logging capabilities for upstream requests.