ENG-8753 docs: add enterprise auth documentation section

[FarhanAliRaza]

Add docs for the OIDC AuthPlugin covering the secure-by-default model, providers, custom auth pages, and testing guarded code. Register the new pages in the enterprise sidebar, add an Authentication category to the enterprise overview, and whitelist the section for preview.

All Submissions:

• Have you followed the guidelines stated in CONTRIBUTING.md file?
• Have you checked to ensure there aren't any other open Pull Requests for the desired changed?

Type of change

Please delete options that are not relevant.

• New feature (non-breaking change which adds functionality)

New Feature Submission:

• Does your submission pass the tests?
• Have you linted your code locally prior to submission?

Changes To Core Features:

• Have you added an explanation of what your changes do and why you'd like us to include them?

[codspeed-hq]

Merging this PR will not alter performance

✅ 26 untouched benchmarks
⏩ 8 skipped benchmarks¹

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_{Comparing FarhanAliRaza:auth-docs (bb830d0) with main (8945367)}

Footnotes

1. 8 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

[greptile-apps]

Greptile Summary

This PR adds a complete enterprise authentication documentation section covering the rxe.AuthPlugin OIDC integration, registers the new pages in the enterprise sidebar, and adds an Authentication category to the enterprise overview. The whitelist.py change removes a stale commented-out entry, leaving the list empty so all pages continue to build.

• Six new markdown docs (overview, secure-by-default, providers, custom-pages, testing, deployment) covering the full AuthPlugin lifecycle from quickstart to production deployment.
• Sidebar and overview wired consistently with the existing enterprise navigation pattern; WHITELISTED_PAGES correctly stays [].

Confidence Score: 5/5

Safe to merge — purely documentation additions and a minor cleanup of a commented-out line in whitelist.py.

All changes are new markdown documentation files plus sidebar/overview wiring that follows the established enterprise page registration pattern exactly. The whitelist.py change removes a commented-out example and leaves the list empty, which is the correct state for building all pages. No functional Python logic is modified.

No files require special attention.

Important Files Changed

Filename	Overview
docs/app/reflex_docs/whitelist.py	Removes commented-out example entry; WHITELISTED_PAGES remains [] (build all pages). Correct change.
docs/app/reflex_docs/templates/docpage/sidebar/sidebar_items/enterprise.py	Adds Authentication section to the enterprise sidebar, referencing enterprise.auth.* path attributes consistent with how other sidebar sections are wired.
docs/enterprise/overview.md	Inserts an Authentication category block with six entries into the overview feature matrix; count matches the sidebar (6 pages).
docs/enterprise/auth/overview.md	New quickstart-oriented overview for rxe.AuthPlugin: install, configure, four protected surfaces, User facade, sign-out, login flow end-to-end.
docs/enterprise/auth/secure-by-default.md	Comprehensive reference for the four auth= wrappers, authorization checks, context objects, withholding mechanics, and CSRF logout protection.
docs/enterprise/auth/providers.md	Documents GenericOIDCAuthState, named providers, env-var resolution, scopes/refresh tokens, multi-provider setup, advanced hooks, and migration from deprecated API.
docs/enterprise/auth/custom-pages.md	Covers page-builder contract, custom login/callback/logout/forbidden builders, auth-failure UX, import-path string wiring, and default builder table.
docs/enterprise/auth/testing.md	Documents unit-testing authorization checks with hand-built context objects, async check testing (includes @pytest.mark.asyncio), and end-to-end OIDC flow against oidc-provider-mock.
docs/enterprise/auth/deployment.md	Covers HTTPS/Secure-cookie requirement, callback URI registration, reverse-proxy considerations, IdP provider table, and troubleshooting table for common deployment errors.

_{Reviews (5): Last reviewed commit: "docs(auth): refine compile-time, check-a..." | Re-trigger Greptile}