refactor to support more flexible tool toggles

[ischneider]

I wanted to introduce a few concepts and use some more features of the framework in an attempt to:

• offer more toggles for tools as groups (e.g. the "sub-server")
• use fastmcp tags, rather than the ignore set, as they can be cross-cutting with different server's tools
• separate out the auto-generated client
• add a custom context (placeholder for now)
• don't use a class or closure to share static dependency (session)

On the latter point, I went with the global lazy-initialized session approach because it's simple. The other approach which I looked at is placing the session in the (new) Planet context but it's less clear how to get the session from the context (the lifecycle context is untyped though we could create a static unwrapper function)

I have a separate MR for the downstream remote server though it's much smaller (but also doesn't support flag parsing yet)

[angaither]

this worked for me after a cache clear (before it the server wouldn't start tho)
is it worth adding anything to the readme for the startup option inputs for this

also fwiw, I agree with steve and perhaps the prefix name should just be sdk without wrapper