K8s: fips content for duckburg

[kaitlynmichael]

Note

Low Risk
Documentation-only changes with no runtime, security logic, or application code impact.

Overview
Adds FIPS 140-3 compliance documentation for Redis Software on Kubernetes: a new fips.md page covering platform prerequisites (FIPS-configured nodes, amd64 only), enabling spec.securityContext.fips.enabled on the RedisEnterpriseCluster, operator behavior (.fips image tag), and digest-pinned image caveats. The Kubernetes Security index gains a Compliance section linking to that page.

Separately, the AI agent builder index adds inline links to vector search and RAG docs in the intro, plus a For experienced developers section pointing to Redis Context Engine and the Redis AI Incubator.

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[github-actions]

Staging links:
https://redis.io/docs/staging/k8s-fips-duckburg/develop/ai/agent-builder/
https://redis.io/docs/staging/k8s-fips-duckburg/operate/kubernetes/security/
https://redis.io/docs/staging/k8s-fips-duckburg/operate/kubernetes/security/fips/

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Cursor Bugbot has reviewed your changes using default effort and found 1 potential issue.

There are 2 total unresolved issues (including 1 from previous review).

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[kaitlynmichael]

@heinrich-redislabs — moving the open FIPS questions out of an in-page draft comment (removed so it doesn't ship in the published page source) into the PR. These are what I need confirmed for the FIPS page:

1. Platforms — OpenShift-in-FIPS-mode only, or also GKE/EKS/AKS with FIPS-configured nodes? (The design doc hinted non-OpenShift may need an env var/configmap hint — did that ship in 8.2.0?)
2. Host prerequisites — what must customers do on the nodes beyond the flag? A link to the relevant Red Hat FIPS doc would help.
3. Scope — is compliance scoped to the Redis Enterprise cluster workload only, not the operator itself? (The operator CSV still sets features.operators.openshift.io/fips-compliant: "false".)
4. arm64 — the FIPS RE image is amd64-only. Does enabling on arm64 fail, or do we just document not to?
5. Verification — recommended way for a customer to confirm the cluster is actually running in FIPS mode?

[mich-elle-luna]

Need to remove the agent-builder files changes, but otherwise is fine, thank you!

[mich-elle-luna]

The changes to this file somehow were added to your commit (this is a separate change I made today to the agent-builder page which was merged)