docs: add short project overview

[SkyBeamProject]

Adds an OVERVIEW.md with a concise project summary.

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Generated by Claude Code

[gemini-code-assist]

Code Review

This pull request introduces an OVERVIEW.md file providing a high-level description of the Python client for the Google Bard API, including authentication details and available interfaces. The review feedback suggests updating the terminology to reflect Google's rebranding of Bard to Gemini and improving the file's readability by breaking down long paragraphs into multiple lines.

[gemini-code-assist]

The project overview is accurate but could be improved for readability and current branding. Google has rebranded Bard to Gemini, so mentioning this would be helpful for users. Also, the line is very long; breaking it into multiple lines improves readability in text editors.

Suggested change

	A reverse-engineered Python client for Google Bard's chatbot API. Authentication is done by supplying the `__Secure-1PSID` and `__Secure-1PSIDTS` cookies from an active bard.google.com session. It exposes synchronous (`Chatbot`) and asynchronous (`AsyncChatbot`) APIs, plus a CLI and a "quick mode" driven by environment variables for shell shortcuts.
	A reverse-engineered Python client for Google Bard's (now Gemini) chatbot API.
	Authentication is done by supplying the __Secure-1PSID and __Secure-1PSIDTS cookies from an active bard.google.com session.
	It exposes synchronous (Chatbot) and asynchronous (AsyncChatbot) APIs, plus a CLI and a "quick mode" driven by environment variables for shell shortcuts.