It clarifies the missing dependencies of all README.md in
python/samples/

- Added explicit mention of required dependencies
- Improved instructions for initial setup

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## Why are these changes needed?
According to issue #6076, several dependencies were missing from the
requirements.txt and not mentioned in the README.md instructions.
This change adds the missing installation instructions to ensure that
users can run the demo smoothly.


## Related issue number
Closes #6076 
<!-- For example: "Closes #1234" -->

## Checks

- [x] I've included any doc changes needed for
<https://microsoft.github.io/autogen/>. See
<https://github.com/microsoft/autogen/blob/main/CONTRIBUTING.md> to
build and test documentation locally.
- [x] I've added tests (if relevant) corresponding to the changes
introduced in this PR.
- [x] I've made sure all auto checks have passed.

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

* add initial global search draft

* add graphrag dep

* fix local search embedding

* linting

* add from config constructor

* remove draft notebook

* update config factory and add docstrings

* add graphrag sample

* add sample prompts

* update readme

* update deps

* Add API docs

* Update python/samples/agentchat_graphrag/requirements.txt

* Update python/samples/agentchat_graphrag/requirements.txt

* update docstrings with snippet and doc ref

* lint

* improve set up instructions in docstring

* lint

* update lock

* Update python/packages/autogen-ext/src/autogen_ext/tools/graphrag/_global_search.py

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

* Update python/packages/autogen-ext/src/autogen_ext/tools/graphrag/_local_search.py

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

* add unit tests

* update lock

* update uv lock

* add docstring newlines

* stubs and typing on graphrag tests

* fix docstrings

* fix mypy error

* + linting and type fixes

* type fix graphrag sample

* Update python/packages/autogen-ext/src/autogen_ext/tools/graphrag/_global_search.py

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

* Update python/packages/autogen-ext/src/autogen_ext/tools/graphrag/_local_search.py

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

* Update python/samples/agentchat_graphrag/requirements.txt

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

* update overrides

* fix docstring client imports

* additional docstring fix

* add docstring missing import

* use openai and fix db path

* use console for displaying messages

* add model config and gitignore

* update readme

* lint

* Update python/samples/agentchat_graphrag/README.md

* Update python/samples/agentchat_graphrag/README.md

* Comment remaining azure config

---------

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