## Why
Amazon Bedrock supports hosted text web search, but it rejects the
`search_content_types` field used for multimodal search and does not support
external live or indexed web access.
## What changed
- Advertise hosted web search for Amazon Bedrock while marking external web
access as unsupported.
- Resolve unsupported live and indexed modes to cached search, or disable the
tool when cached search is prohibited by managed requirements.
- Normalize built-in and configured Bedrock model catalogs to text-only web
search, and retain the runtime provider in session configuration so turn
setup can apply its capabilities.
## Testing
- Cover cached fallback, managed-mode restrictions, text-only tool payloads,
provider capabilities, and catalog normalization.
GitOrigin-RevId: 310473849257401654388a4ebb42920e03aa3228
3044612e13