Update manual OAuth capability sync documentation

[kennyj42]

Summary

• document immediate capability discovery after administrator authorization
• cover manual and periodic resync for stored OAuth credentials
• align stale credential status and troubleshooting guidance
• remove the obsolete manual OAuth limitation and add an Access changelog entry

Testing

• pnpm run check:astro
• git diff --check

[github-actions]

This pull request requires reviews from CODEOWNERS as it changes files that match the following patterns:

Pattern	Owners
/src/content/changelog/access/	@asamborski, @cloudflare/pm-changelogs, @cloudflare/product-owners
/src/content/docs/cloudflare-one/access-controls/	@asamborski, @kennyj42, @cloudflare/cf1-reviewers, @cloudflare/product-owners

[cloudflare-workers-and-pages]

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[github-actions]

Preview URL: https://1661adcd.preview.developers.cloudflare.com
Preview Branch URL: https://kjohnson-document-manual-oauth-sync.preview.developers.cloudflare.com

Files with changes (up to 15)

Original Link	Updated Link
https://developers.cloudflare.com/cloudflare-one/access-controls/ai-controls/mcp-portals/	https://kjohnson-document-manual-oauth-sync.preview.developers.cloudflare.com/cloudflare-one/access-controls/ai-controls/mcp-portals/
https://developers.cloudflare.com/changelog/post/2026-09-10-mcp-manual-oauth-capability-sync/	https://kjohnson-document-manual-oauth-sync.preview.developers.cloudflare.com/changelog/post/2026-09-10-mcp-manual-oauth-capability-sync/