Add back personalization information

[ethanpalm]

Documentation changes

Personalization info got caught up in the auth consolidation. This PR adds it back, but places it more logically in the creating content section rather than as a subset of auth.

Closes https://linear.app/mintlify/issue/DOC-248/add-personalization-content-docs-back-to-authentication-setup

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For Reviewers

When reviewing documentation PRs, please consider:

✅ Technical accuracy

• Code examples work as written
• Commands and configurations are correct
• Links resolve to the right destinations
• Prerequisites and requirements are accurate

✅ Clarity and completeness

• Instructions are clear and easy to follow
• Steps are in logical order
• Nothing important is missing
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✅ User experience

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• Common gotchas or edge cases are addressed
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Note

Low Risk
Low risk documentation-only changes (new page, examples, and navigation/redirect updates) with no runtime code impact; main risk is broken links or confusing guidance if examples are inaccurate.

Overview
Adds a new create/personalization doc page describing user-specific features (API playground prefill, dynamic MDX via user, group-based page visibility, and OpenAPI filtering including oneOf and enum value gating).

Updates deploy/authentication-setup to reflect these personalization capabilities by expanding User data format/docs and OAuth/JWT examples (adds content and apiPlaygroundInputs), and clarifies that password auth doesn’t support these features. Updates site navigation to include the new page, un-hides the Analytics API group, and redirects /deploy/personalization-setup to the new page; adds Vale vocabulary allowances for enum and oneOf.

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