docs: clarify that Glanceboard requires a Gemini API key

[raphdixon]

The README previously stated "fully local" and "no cloud account needed," which is misleading since a Gemini API key is required for image generation and intelligence features.

Changes

• Updated "no cloud account needed" → clarifies the server runs locally or can be deployed to the cloud, but requires a Gemini API key
• Updated "Fully local" → "Self-hosted" with a note that a Gemini API key is required
• Both references now link to the existing API key setup section

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[gemini-code-assist]

Code Review

This pull request updates the README.md to reflect that the application requires a Gemini API key and can be self-hosted locally or deployed to the cloud. The review feedback points out a grammatical inconsistency in the self-hosted description and suggests a correction to maintain parallelism.

[gemini-code-assist]

The phrase "Runs on your own machine or deploy to the cloud" is grammatically inconsistent because it mixes the third-person verb "Runs" with the base verb "deploy". Updating it to "can be deployed" ensures grammatical parallelism and consistency with the rest of the document.

Suggested change

	- **Self-hosted** — Runs on your own machine or deploy to the cloud; requires a [Gemini API key](#api-key-setup)
	- **Self-hosted** — Runs on your own machine or can be deployed to the cloud; requires a [Gemini API key](#api-key-setup)