cloud: merge premium IAM into shared user access docs

[qiancai]

What is changed, added or deleted? (Required)

This PR consolidates the Premium identity access management content into the shared TiDB Cloud IAM documentation and updates related TiDB X terminology across the Cloud docs.

• Replaces the Premium TOC entry with the shared Identity Access Management page.
• Deletes the Premium-only IAM page and updates Premium doc links to point to the shared IAM document.
• Updates key concepts, project/resource, security, and glossary content so TiDB X references consistently include Premium instances.
• Validation: ./scripts/verify-links.sh, ./scripts/verify-link-anchors.sh, and node ./scripts/verify-internal-links-in-toc.js.

Which TiDB version(s) do your changes apply to? (Required)

• master (the latest development version)
• v8.5 (TiDB 8.5 versions)
• v8.4 (TiDB 8.4 versions)
• v8.3 (TiDB 8.3 versions)
• v8.2 (TiDB 8.2 versions)
• v8.1 (TiDB 8.1 versions)
• v7.5 (TiDB 7.5 versions)
• v7.1 (TiDB 7.1 versions)
• v6.5 (TiDB 6.5 versions)
• v6.1 (TiDB 6.1 versions)
• v5.4 (TiDB 5.4 versions)
• v5.3 (TiDB 5.3 versions)

What is the related PR or file link(s)?

• This PR is translated from:
• Other reference link(s):

Do your changes match any of the following descriptions?

• Delete files
• Change aliases
• Need modification after applied to another branch
• Might cause conflicts after applied to another branch

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[gemini-code-assist]

Code Review

This pull request significantly reorganizes the TiDB documentation to highlight AI capabilities, introducing a new /ai/ directory with extensive guides and examples for vector search, full-text search, and auto-embedding. It also updates the documentation for TiDB v8.5, adds content for the TiKV MVCC in-memory engine and batch processing, and improves Backup & Restore (BR) documentation. The review feedback focuses on ensuring consistency through the use of product placeholders, preferring internal documentation links, and improving readability by using active voice and concise phrasing.

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ai/guides/connect.md (25)

For consistency with other documentation pages, please use the {{{ .starter }}} placeholder instead of hardcoding "TiDB Cloud Starter". This also applies to lines 27, 49, 84, 86, and 101 in this file.

<div label="{{{ .starter }}}">

References

1. Use consistent terminology and prefer placeholders where applicable for product names. ^(link)

ai/guides/vector-search.md (216-219)

It is recommended to use internal links for TiDB documentation pages instead of external URLs to the TiDB Cloud documentation site.

| [`VEC_L2_DISTANCE`](/ai/reference/vector-search-functions-and-operators.md#vec_l2_distance)                       | Calculates L2 distance (Euclidean distance) between two vectors |
| [`VEC_COSINE_DISTANCE`](/ai/reference/vector-search-functions-and-operators.md#vec_cosine_distance)               | Calculates the cosine distance between two vectors              |
| [`VEC_NEGATIVE_INNER_PRODUCT`](/ai/reference/vector-search-functions-and-operators.md#vec_negative_inner_product) | Calculates the negative of the inner product between two vectors|
| [`VEC_L1_DISTANCE`](/ai/reference/vector-search-functions-and-operators.md#vec_l1_distance)                       | Calculates L1 distance (Manhattan distance) between two vectors |

ai/guides/vector-search.md (292)

Please use an internal link for SQL operators. This also applies to lines 365 and 404.

As a relational database, TiDB supports a rich set of [SQL operators](/functions-and-operators/operators.md) and allows flexible combinations of filtering conditions.

ai/guides/vector-search-full-text-search-python.md (69)

Please use the {{{ .essential }}} placeholder for consistency with the {{{ .starter }}} placeholder used in the same sentence.

1. Navigate to the [**My TiDB**](https://tidbcloud.com/tidbs) page, and then click the name of your target {{{ .starter }}} or {{{ .essential }}} instance to go to its overview page.

api/tidb-cloud-api-v1beta1.md (19)

This entry is missing a description. Please add a brief explanation of what the MSP API manages, consistent with the other entries in this list.

    - [MSP (Deprecated)](https://docs.pingcap.com/tidbcloud/api/v1beta1/msp): manage Managed Service Provider (MSP) resources.

br/br-pitr-guide.md (57)

The preposition "in" is more appropriate than "at" when referring to a dashboard within a software platform like Grafana.

- `speed(est.)`: the current data transfer rate of the log backup. This value is estimated based on traffic samples taken in the past few seconds. For more accurate traffic statistics, you can check the `Log Backup` row in the **[TiKV-Details](/grafana-tikv-dashboard.md#tikv-details-dashboard)** dashboard in Grafana.

br/br-pitr-manual.md (506)

This sentence can be made more concise by removing unnecessary words.

Starting from TiDB v8.5.5, you can use filters during PITR to restore specific databases or tables for more fine-grained control.

References

1. Avoid unnecessary words and repetition. ^(link)

br/br-pitr-manual.md (587)

Prefer active voice and remove unnecessary parenthetical phrases for better readability.

Starting from v8.5.5, when a log backup task is running, if all of the following conditions are met, you can still perform snapshot restore (`br restore [full|database|table]`) and the ongoing log backup records the restored data:

References

1. Avoid passive voice and unnecessary words. ^(link)

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[LGTM Timeline notifier]

Timeline:

• 2026-04-24 08:53:11.40326956 +0000 UTC m=+2328796.608629607: ☑️ agreed by Oreoxmt.