feat(bedrock): add prompt cache TTL support

[imdigitalashish]

Add configurable TTL ('5m' or '1h') for Bedrock prompt caching. Previously all cache settings were boolean-only. Now bedrock_cache_instructions, bedrock_cache_tool_definitions, and bedrock_cache_messages accept bool | Literal['5m', '1h'], and CachePoint(ttl=...) is forwarded to the Bedrock API.

Closes #4096

• Closes #

Pre-Review Checklist

• Any AI generated code has been reviewed line-by-line by the human PR author, who stands by it.
• No breaking changes in accordance with the version policy.
• Linting and type checking pass per make format and make typecheck.
• PR title is fit for the release changelog.

Pre-Merge Checklist

• New tests for any fix or new behavior, maintaining 100% coverage.
• Updated documentation for new features and behaviors, including docstrings for API docs.

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Summary by cubic

Adds TTL support to Amazon Bedrock prompt caching so you can set '5m' or '1h' instead of only on/off. TTL applies to system instructions, tool definitions, the last user message, and manual CachePoint. Closes #4096.

• New Features

  • bedrock_cache_instructions, bedrock_cache_tool_definitions, and bedrock_cache_messages accept bool | '5m' | '1h'; TTL is sent only when a string is provided, otherwise omitted. CachePoint(ttl='5m'|'1h') is forwarded to Bedrock. Updated CachePoint.ttl docs to include Bedrock, clarify TTL omission for Anthropic via Bedrock, and add the missing docstring for the cache_point parameter.

• Dependencies

  • Upgrade boto3 and boto3-stubs to 1.42.63.

^{Written for commit 89018eb. Summary will update on new commits.}

[devin-ai-integration]

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[rand-davis-ssc]

I'd love to see this merged - this would directly help reduce costs.