docs: Bedrock model name is an invocation ID (TH-3486)

[nik13]

Summary

• Stop calling Bedrock Model Name a friendly label. It is the AWS foundation-model or system inference-profile ID (for example anthropic.claude-3-haiku-20240307-v1:0 or us.anthropic.claude-3-5-sonnet-20241022-v2:0).
• State the limits of the form: no model training or import in AWS, Save sends a small validation request that can incur provider charges, and application-profile ARNs, provisioned throughput and session-token or role credentials are not supported.
• Redirect the retired /docs/evaluation/features/custom-models path to the canonical guide.
• Pairs with fix: reject Bedrock display labels on evaluator custom models (TH-3486) future-agi#3291, which rejects family labels such as Claude before the validation call with a clear error. The page is accurate whether or not #3291 has shipped: today a family label already fails at the validation call (Unknown provider=None, model=Claude), so this can merge independently. Spec: company-brain PR traceAI install #56.

Test plan

• Two-file diff only (guide and redirect map), up to date with main, no conflicts
• PR check "Link audit & redirect enforcement" passed on this head
• Local npm run audit-links: 0 broken nav links, 0 broken content links; check-deleted-pages.mjs main: no pages deleted
• Local astro build (Node 26, same lockfile): 1182 pages built, exit 0; dist/docs/evaluation/features/custom-models/ is a redirect to /docs/evaluation/guides/custom-models. The build's two route-conflict warnings (/docs/sdk/tracing, /docs/sdk/annotation-queues) are unrelated to this diff.
• Independent docs review on this head: no findings

Video demo

The product walkthrough is on the app PR (future-agi/future-agi#3291). This docs PR has no runnable UI.