Find a better way to pin SDK code gen dependencies without affecting emitter dependencies

To influence the content of emitter-package.json, we update the emitter's package.json with a peerDependency and matching pinned devDependency. This has the desired effect on emitter-package.json, but we end up declaring peer dependencies that the emitter doesn't actually depend on.

We need a new way to accommodate:
- Produce a emitter-package.json and lock file programmatically from an emitter build or from a published emitter package
- emitter-package-lock.json construction should be deterministic
- emitter-package.json shouldn't be so complex that it's difficult to diff the emitter version bump

Start by locating the code that updates emitter-package.json and constructs emitter-package-lock.json, then trace whether it runs from an emitter build or a published emitter package. Done means dependency pinning no longer adds unrelated emitter peer dependencies, lock-file construction is deterministic, and emitter-package.json remains easy to diff during version bumps.

Written by the indexing model from the issue text.