Python: Add load_dotenv() to samples for .env file support (#4043)

* Initial plan

* Add load_dotenv() to 303 Python samples for environment variable loading

Co-authored-by: TaoChenOSU <12570346+TaoChenOSU@users.noreply.github.com>

* Update SAMPLE_GUIDELINES.md to document load_dotenv() requirement

Co-authored-by: TaoChenOSU <12570346+TaoChenOSU@users.noreply.github.com>

* Update samples README.md to document .env file usage

Co-authored-by: TaoChenOSU <12570346+TaoChenOSU@users.noreply.github.com>

* Run ruff format on all changed sample files

Co-authored-by: TaoChenOSU <12570346+TaoChenOSU@users.noreply.github.com>

* Clarify load_dotenv() usage in README - local dev vs production

Co-authored-by: TaoChenOSU <12570346+TaoChenOSU@users.noreply.github.com>

* Remove deprecated getting_started folder as requested

Co-authored-by: TaoChenOSU <12570346+TaoChenOSU@users.noreply.github.com>

* Document env_file_path parameter for per-client configuration

Co-authored-by: TaoChenOSU <12570346+TaoChenOSU@users.noreply.github.com>

* Merge main branch to resolve conflicts

Co-authored-by: TaoChenOSU <12570346+TaoChenOSU@users.noreply.github.com>

* Fix run_evaluation.py file that was empty in merge commit

Co-authored-by: TaoChenOSU <12570346+TaoChenOSU@users.noreply.github.com>

* Remove dotnet changes from merge - out of scope for this PR

Co-authored-by: TaoChenOSU <12570346+TaoChenOSU@users.noreply.github.com>

* Remove package and test changes from merge - only sample changes needed

Co-authored-by: TaoChenOSU <12570346+TaoChenOSU@users.noreply.github.com>

* Remove test_func_utils.py - only sample changes needed

Co-authored-by: TaoChenOSU <12570346+TaoChenOSU@users.noreply.github.com>

* Revert sample files not in original changeset - keep only load_dotenv additions

Co-authored-by: TaoChenOSU <12570346+TaoChenOSU@users.noreply.github.com>

* Move load_dotenv() outside snippet tag in 06_host_your_agent.py

Co-authored-by: TaoChenOSU <12570346+TaoChenOSU@users.noreply.github.com>

* Fix comment placement - move load_dotenv before code comments

Co-authored-by: TaoChenOSU <12570346+TaoChenOSU@users.noreply.github.com>

* Fix load_dotenv() placement across all samples - after docstring, before code comments

Co-authored-by: TaoChenOSU <12570346+TaoChenOSU@users.noreply.github.com>

* Merge latest main branch with load_dotenv changes

Co-authored-by: TaoChenOSU <12570346+TaoChenOSU@users.noreply.github.com>

* Remove non-sample changes from merge - keep only load_dotenv additions

Co-authored-by: TaoChenOSU <12570346+TaoChenOSU@users.noreply.github.com>

* Revert non-load_dotenv sample changes from merge

Co-authored-by: TaoChenOSU <12570346+TaoChenOSU@users.noreply.github.com>

* Fix run_evaluation.py - use main's improved version (file already had load_dotenv)

Co-authored-by: TaoChenOSU <12570346+TaoChenOSU@users.noreply.github.com>

* Manual update

* Manual update 2

* Fix Role usage and load_dotenv placement per PR review feedback

Co-authored-by: eavanvalkenburg <13749212+eavanvalkenburg@users.noreply.github.com>

* Fix Role usage - use string literals not enum attributes

Co-authored-by: eavanvalkenburg <13749212+eavanvalkenburg@users.noreply.github.com>

* Fix SAMPLE_GUIDELINES.md example - load_dotenv before docstring per guidance

Co-authored-by: eavanvalkenburg <13749212+eavanvalkenburg@users.noreply.github.com>

* Move load_dotenv() before docstrings in all samples per SAMPLE_GUIDELINES ordering

Co-authored-by: eavanvalkenburg <13749212+eavanvalkenburg@users.noreply.github.com>

* Address PR review: rename files, fix placement, add session usage, remove note

Co-authored-by: eavanvalkenburg <13749212+eavanvalkenburg@users.noreply.github.com>

* Update Redis README to reference renamed file redis_history_provider.py

Co-authored-by: eavanvalkenburg <13749212+eavanvalkenburg@users.noreply.github.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: TaoChenOSU <12570346+TaoChenOSU@users.noreply.github.com>
Co-authored-by: Tao Chen <taochen@microsoft.com>
Co-authored-by: eavanvalkenburg <13749212+eavanvalkenburg@users.noreply.github.com>
Co-authored-by: Eduard van Valkenburg <eavanvalkenburg@users.noreply.github.com>

python/samples/02-agents/middleware/function_based_middleware.py

@@ -13,8 +13,12 @@ from agent_framework import (
 )
 from agent_framework.azure import AzureAIAgentClient
 from azure.identity.aio import AzureCliCredential
+from dotenv import load_dotenv
 from pydantic import Field
 
+# Load environment variables from .env file
+load_dotenv()
+
 """
 Function-based MiddlewareTypes Example
 
@@ -31,7 +35,9 @@ can be implemented as async functions that accept context and call_next paramete
 """
 
 
-# NOTE: approval_mode="never_require" is for sample brevity. Use "always_require" in production; see samples/02-agents/tools/function_tool_with_approval.py and samples/02-agents/tools/function_tool_with_approval_and_sessions.py.
+# NOTE: approval_mode="never_require" is for sample brevity. Use "always_require" in production;
+# see samples/02-agents/tools/function_tool_with_approval.py
+# and samples/02-agents/tools/function_tool_with_approval_and_sessions.py.
 @tool(approval_mode="never_require")
 def get_weather(
     location: Annotated[str, Field(description="The location to get the weather for.")],