Extends the Metadata class from @decaf-ts/decoration with Metadata.nodes() and Metadata.workflows() accessors that return all @node-decorated and @graph-decorated constructors respectively.

This follows the existing override pattern used by core (core/src/overrides/) and decorator-validation (decorator-validation/src/overrides/):

1. This file declares the new static methods on the Metadata namespace via declare module (TypeScript declaration merging).
2. The companion overrides.ts attaches the implementations to the Metadata class at runtime via (Metadata as any).fn = ....
3. The index.ts of this folder side-effect-imports overrides.ts so the attachments run whenever the graph module is loaded.
4. The package's sideEffects array in package.json includes the compiled overrides entry points so bundlers preserve the side-effect imports.