* Readme edits to support the team

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Co-authored-by: Jack Gerrits <jackgerrits@users.noreply.github.com>

closes #3950 closes #3702

What this is doing:

I am refactoring the services on the .NET runtime and attempting to clarify the naming and organization.
I added this doc to help capture the naming and concepts.
AgentRuntime / Worker should work similar to the python version and enables running the whole agent system in one process. For remote the system uses the versions of the services in the grpc folder.
lots of other bug fixes/threading cleanup - passing cancellation token throughout
Services update clarifies the naming and roles:

Worker: Hosts the Agents and is a client to the Gateway
Gateway:
-- RPC gateway for the other services APIs
-- Provides an RPC bridge between the workers and the Event Bus
Registry: keeps track of the agents in the system and which events they can handle
AgentState: persistent state for agents

* Update version to dev4

* Update dev version

* Update uv

* C#

* update versions

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Co-authored-by: Jack Gerrits <jack@jackgerrits.com>
Co-authored-by: Jack Gerrits <jackgerrits@users.noreply.github.com>

* test multiversion build

* Work on multiversion build

* update refs

* cancel in progress

* add docs dir

* add version switcher

* add version switcher

* add preferred

* version banner and hacky value override...

* add release version

Co-authored-by: Eric Zhu <ekzhu@users.noreply.github.com>

* Standardize Agent and Topic ID strings + documentation

* Add specs

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Co-authored-by: Jack Gerrits <jackgerrits@users.noreply.github.com>

Moves some shared code from samples into core.
complete/cleanup the rename to Microsoft.AutoGen
adds new projects in AutoGen.Extensions

* host agent runtime API and docs

* graceful shutdown of worker

* HostAgentRuntime --> WorkerAgentRuntimeHost

* Add unit tests for worker runtime

* Fix bug in worker runtime adding sender filed to proto. Documentation.

* wip

* Fix unit tests; refactor API

* fix formatting

* Fix

* Update

* Make source field optional in Event proto

* Add design doc for routing

* rename

* add explanations

* Update 02 - Message routing.md

* add examples, rename to type

* add naming clarification

* add regex

* update spec based on feedback

* Remove open question

* remove _ from send/pub, add docs,

* fixes

* Move agent creation into the runtime

* update doc

* add test

* Remove limitation of subscriptions being same across namespaces

* constrain agent types to namespaces

* migrate name, desc, subs to metadata

* fix quote in f string

* remove file

* add metadata func to runtime

* format

* initial docs

* update docs

* Update agent.md

* Update memory.md

* Update runtime.md

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Co-authored-by: Jack Gerrits <jackgerrits@users.noreply.github.com>

* Organize some more modules

* cleanup model_client

* Add doc about how to use aad for model client

* update after testing

* Add initial docs site

* add ci and readme

* Update checks.yml

* Update conf.py