Set up a Python mono repo in Visual Studio Code

[samj]

Currently we have several largely independent components (frontend, backend, etc.) and abilities (llamafile, chromadb, etc.) that could be well-served by having their own settings, dependencies, etc. rather than trying to coexist in the same container (i.e., the paios repo folder).

Per Microsoft's Mono Repo Set‐up Guide, it may make sense for us to move from Scenario 1: Shared Dependencies to Scenario 2: Separate Virtual Environments using Visual Studio Code's multi-root workspaces and a dedicated monorepo build tool like Pants (and the Suspenders plugin).