[Feature Request] Create a separate "core" library for workflows that does not include bundler deps.

Is your feature request related to a problem? Please describe.

Dependencies are structured in @temporalio/worker's package.json such that there is no way to not include webpack + @swc/core in a runtime build, because @temporalio/worker includes them in dependencies regardless of whether runtime bundling is required or not.

@swc/core is around ~150MB, so it adds a lot of bloat to distroless images and goes completely unused if workflow bundling has already happened in a separate build step, which is common in containerized build processes.

Describe the solution you'd like

It would be great if we had a runtime package (e.g. @temporalio/worker-core) which just contained minimal deps for running a worker and excluded bundler components. It could itself be a dependency of the full @temporalio/worker for compatibility.

Additional context

I added an example build with a step to manually strip out bundler dependencies here:
https://github.com/psigen/temporal-ts-example/blob/main/Dockerfile#L77

This reduced runtime images by almost 200MB, to a pretty manageable <300MB overall size for a distroless image.

Original idea from this slack thread

Start by inspecting @temporalio/worker's package.json and the example Dockerfile at line 77 to understand the current dependency layout and runtime stripping approach. Define the package boundary and compatibility relationship so a runtime package excludes webpack and @swc/core while the full worker package remains usable.