Generate conformance-test SAM templates from handler metadata

## Summary

PR #552 adds hand-maintained SAM templates for the Java conformance test suites. Each handler requires a largely repetitive Lambda resource plus a `TestingMetadata.TestDescription` mapping to conformance requirement IDs. As the number of handlers and suites grows, maintaining these mappings in both Java code and SAM YAML will be error-prone.

Add a script or build step that generates the conformance-test SAM templates from handler metadata.

Review context: https://github.com/aws/aws-durable-execution-sdk-java/pull/552#discussion_r3617917672

## Requirements

- Define one source of truth for the mapping between each Java handler and its conformance requirement IDs. This could be a Java annotation, a small manifest, or another explicit convention.
- Generate `template_.yaml` files deterministically for all conformance suites.
- Preserve the shared SAM configuration and each function's `TestingMetadata.TestDescription` values.
- Integrate generation into the local/CI conformance-test workflow so templates cannot silently drift from handlers or metadata.
- Document how to add a handler and its requirement mapping to an existing or new suite.

## Acceptance criteria

- Adding or removing a conformance handler requires no manual duplication of its Lambda resource in a SAM template.
- Generated templates pass SAM validation/build and run the existing step and wait conformance suites successfully.
- Generation is stable: running it twice without source changes produces no diff.
- CI fails when checked-in generated templates are stale, or generates templates before they are consumed if they are not checked in.

PR #552 と既存の手作業で管理されている conformance-test SAM templates から始め、Java handlers とその TestingMetadata.TestDescription mappings を追跡します。local/CI conformance-test workflow を SAM validation/build、および step と wait suites と比較します。完了の条件は、決定的な templates、文書化された handler registration、成功する suite runs、そして古い生成出力から保護する CI です。

索引モデルが issue の本文から書いたものです。