fix(policy): support generated policy definitions - #2021

Description

agentcore add policy --generate assumed generated statements always used
definition.cedar.statement. After the Policy service's Dogwood rollout, valid generated
statements can instead use definition.policy.statement, causing the CLI to report that no Cedar
statement was found even though generation succeeded.

This change:

• accepts generated statements from either supported PolicyDefinition member
• surfaces service findings when an asset contains no statement
• adds SDK-boundary regression tests for Cedar, Policy, and invalid generation assets

Related Issue

Closes #2020

Documentation PR

N/A - this restores the documented policy generation behavior.

Type of Change

• Bug fix
• New feature
• Breaking change
• Documentation update
• Other (please describe):

Testing

How have you tested the change?

• I ran npm run test:unit and npm run test:integ
• I ran npm run typecheck
• I ran npm run lint
• If I modified src/assets/, I ran npm run test:update-snapshots and committed the updated snapshots (N/A - no asset changes)

Focused unit tests:

npx vitest run --project unit \
  src/cli/aws/__tests__/policy-generation.test.ts \
  src/cli/primitives/__tests__/PolicyPrimitive.test.ts

Test Files  2 passed (2)
Tests      10 passed (10)

Also verified the changed files with Prettier and git diff --check.

Checklist

• I have read the CONTRIBUTING document
• I have added any necessary tests that prove my fix is effective or my feature works
• I have updated the documentation accordingly (N/A - no documentation change required)
• I have added an appropriate example to the documentation to outline the feature, or no new docs are needed
• My changes generate no new warnings
• Any dependent changes have been merged and published

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terms of your choice.