feat: folder hash

[brunozoric]

Summary

Add HashFolderTool to @webiny/stdlib/node as a zero-dependency replacement for the unmaintained folder-hash library.

• Deterministic SHA-256 folder hashing: walks the directory tree, hashes each file, sorts by relative path, combines into a single digest
• Two methods: hash (sync) and hashAsync (parallel I/O via Promise.all)
• Supports excludeFolders and excludeFiles options to skip build artifacts (dist, node_modules, tsbuildinfo, etc.)
• Returns HashFolderResult object ({ hash: string }) for future extensibility
• Three consumption modes: DI abstraction (HashFolderTool/HashFolderToolFeature), factory (createHashFolderTool), standalone functions (hashFolder/hashFolderAsync)
• Full test coverage with 23 tests covering determinism, excludes, renames, empty folders, order-independence, and sync/async parity

Usage

const { hash } = hashFolder(workspacePackage.packageFolder, {
    excludeFolders: ["dist", "lib", "node_modules"],
    excludeFiles: ["tsconfig.build.tsbuildinfo"]
});

Test plan

• All 365 tests pass (342 existing + 23 new)
• 100% coverage on HashFolderTool implementation
• No regressions in existing tests
• Pre-commit chain clean (yarn, adio, format, lint, typecheck, build, test:coverage)