New pattern submission - lambda-durable-agentcore-springai-sam-java

To submit a template to the Serverless Patterns Collection, per the simplified process all pattern metadata (description, language, level, framework, intro, resources, deploy/test/cleanup, author) is provided in the `example-pattern.json` file included in the PR.

**Pattern:** lambda-durable-agentcore-springai-sam-java
**Summary:** Human-in-the-loop AI review with AWS Lambda durable functions and Amazon Bedrock AgentCore, in Java. A durable function orchestrates a Spring AI agent hosted on AgentCore Runtime: the agent drafts a summary of a submitted document and flags what a reviewer should verify, the workflow suspends at a `waitForCallback` until a human approves or rejects, and on approval the agent produces a final version incorporating the reviewer's comments. No compute is billed while suspended, and the completed agent step is served from its checkpoint on resume rather than being re-invoked. Workflow state is checkpointed by the durable execution service and read back with `get-durable-execution`, so the pattern provisions no database. Two services: AWS Lambda and Amazon Bedrock AgentCore.

**Language:** Java
**Framework:** AWS SAM
**Level:** 300 (Advanced)

## GitHub PR for template:
https://github.com/aws-samples/serverless-patterns/pull/3264

Start with the linked pull request #3264 and the included example-pattern.json, which contains the pattern metadata. Review the Java AWS SAM template and its deploy, test, and cleanup instructions; done means the pattern submission and metadata are complete and consistent with the described durable workflow.

Written by the indexing model from the issue text.