refactor(storage): extract SSM provider capabilities

[edersonbrilhante]

Description

• add a storage-provider runtime package with separate RunnerBootstrapStore and RunnerGroupCacheStore capability contracts
• keep aws_ssm as the only implementation while preserving existing parameter paths, SecureString/String behavior, tags, throughput pacing, IAM, KMS behavior, and Terraform resource addresses
• select SSM independently for bootstrap handoff and runner-group caching in stable and experimental scale-up/pool Lambdas
• rename compute-provider metadata hooks so shared contracts no longer expose SSM-specific tag names
• document the usage-based storage boundary and explicitly defer credentials, persistent configuration, AMI resolution, runner-side reads, and DynamoDB

Test Plan

• yarn vitest run --config libs/storage-providers/vitest.config.ts — 49 files / 819 tests passed
• TypeScript compile checks passed for storage-providers and control-plane
• ESLint and Prettier checks passed for the changed TypeScript sources
• the control-plane Lambda bundled successfully with ncc
• tofu test -filter=tests/pool.tftest.hcl passed for the stable runners module
• the changed primary scenarios passed in the webhook scale-runners and pool Terraform tests; later pre-existing override scenarios remain blocked locally by OpenTofu resolving var.config as unavailable inside their run-level variable blocks
• staged pre-commit checks passed: Terraform fmt, Terraform validate with TFLint, and merge-conflict detection

Related Issues

None.

[github-actions]

Dependency Review

The following issues were found:

• ✅ 0 vulnerable package(s)
• ✅ 0 package(s) with incompatible licenses
• ✅ 0 package(s) with invalid SPDX license definitions
• ⚠️ 2 package(s) with unknown licenses.

See the Details below.

License Issues

lambdas/functions/control-plane/package.json

Package	Version	License	Issue Type
@aws-github-runner/storage-providers		Null	Unknown License

lambdas/libs/storage-providers/package.json

Package	Version	License	Issue Type
@aws-github-runner/aws-ssm-util		Null	Unknown License

OpenSSF Scorecard

Package	Version	Score	Details
npm/@aws-github-runner/storage-providers		Unknown	Unknown
npm/@aws-github-runner/aws-ssm-util		Unknown	Unknown

Scanned Files

• lambdas/functions/control-plane/package.json
• lambdas/libs/storage-providers/package.json