Remove tool usage for non current turns when looking up message history

[sobolk]

Problem

Tool use and result blocks become irrelevant after turn is completed.
We persist "client side tools" blocks in history (as they require UI -> Appsync -> Lambda -> Bedrock roundtrip to work).

Including non-current turn's tools blocks in message history isn't incorrect but it costs tokens to process by Bedrock. Therefore, we remove them.

Changes

Add logic to message history retrieval that:

1. Finds where current turn begins
2. Removes any tool use/result blocks from non-current turns.
3. Squashes messages that belong to the same "role" (in case tool removal leaves continuous sequences of them).

Validation

1. Added unit test with most extreme case.
2. Existing unit tests cover the rest.

Checklist

• If this PR includes a functional change to the runtime behavior of the code, I have added or updated automated test coverage for this change.
• If this PR requires a change to the Project Architecture README, I have included that update in this PR.
• If this PR requires a docs update, I have linked to that docs PR above.
• If this PR modifies E2E tests, makes changes to resource provisioning, or makes SDK calls, I have run the PR checks with the run-e2e label set.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[changeset-bot]

🦋 Changeset detected

Latest commit: c321517

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@aws-amplify/ai-constructs	Patch

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