docs(ai-gateway): tighten authentication wording

[wixysam]

Summary

Follow-up to #330. JSDoc wording changes in packages/sdk/src/modules/ai-gateway.types.ts, matching edits made on base44-dev/mintlify-docs#2569.

• Service role bullet: split the semicolon sentence into short sentences and name what gets the 403 (calls from the browser or with a user's token).
• token field: replaced the two-token description and the "gateway expects the service-role token" sentence, which contradicted the user authentication bullet, with one sentence saying the calling mode determines whose token it is.
• Authentication Modes: added the paragraph on what the mode changes. It exists on the mintlify page but was never in the SDK source, so a docs regeneration would remove it. The first sentence now says the mode decides which token you get and whether the gateway accepts the call.

Verified by running npm run create-docs and diffing the generated ai-gateway.mdx against the mintlify page for these sections. One cosmetic difference: the generator renders inline code in the token field with double backticks.

🤖 Generated with Claude Code

[github-actions]

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