Python: restructure: Python samples into progressive 01-05 layout (#3862)

* restructure: Python samples into progressive 01-05 layout

- 01-get-started/: 6 numbered steps (hello agent → hosting)
- 02-agents/: all agent concept samples (tools, middleware, providers, etc.)
- 03-workflows/: ALL existing workflow samples preserved as-is
- 04-hosting/: azure-functions, durabletask, a2a
- 05-end-to-end/: demos, evaluation, hosted agents
- Old files moved to _to_delete/ for review
- Added AGENTS.md with structure documentation
- autogen-migration/ and semantic-kernel-migration/ preserved at root

* fix: switch to AzureOpenAI Foundry, fix CI failures

- Switch all 01-get-started samples to AzureOpenAIResponsesClient with
  Azure AI Foundry project endpoint (AZURE_AI_PROJECT_ENDPOINT +
  AZURE_OPENAI_RESPONSES_DEPLOYMENT_NAME + AzureCliCredential)
- Add _to_delete/ and 05-end-to-end/ to pyrightconfig.samples.json excludes
- Fix test paths in packages/ that referenced old getting_started/ dirs:
  durabletask conftest + streaming test, azurefunctions conftest,
  devui conftest + capture_messages + openai_sdk_integration
- Fix workflow_as_agent_human_in_the_loop.py import (sibling import)
- Update hosting READMEs and tool comment paths
- Replace root README.md with new structure overview
- Update AGENTS.md to document Azure OpenAI Foundry as default provider

* cleanup: remove _to_delete folder, copy resource files to active dirs

All files in _to_delete/ were either:
- Exact duplicates of files in the new structure (240 files)
- Same file with only comment path updates (100 files)
- One import-fix diff (workflow_as_agent_human_in_the_loop.py)
- One superseded minimal_sample.py

Resource files (sample.pdf, countries.json, employees.pdf, weather.json)
copied to 02-agents/sample_assets/ and 02-agents/resources/ since active
samples reference them.

* fix: address PR review comments, centralize resources, remove root duplicates

- Fix type annotation in 04_memory.py (string union -> proper types)
- Fix old sample paths in observability files
- Fix grammar/spelling in observability samples
- Move sample_assets/ and resources/ to shared/ folder
- Remove 8 duplicate observability files from 02-agents root
- Update resource path references in multimodal_input and provider samples

* fix: update broken links from old getting_started paths to new structure

- Update relative paths in READMEs: getting_started/ → 01-get-started/,
  02-agents/, 03-workflows/, 04-hosting/, 05-end-to-end/
- Fix absolute GitHub URLs in package READMEs
- Fix broken link in ollama package README

* fix: convert absolute GitHub URLs to relative paths for link checker

Absolute URLs to python/samples/ on main branch 404 until PR merges.
Converted to relative paths that linkspector can verify locally.

* fix: update link for handoff sample moved to orchestrations/

* fix: update chatkit-integration README path from demos/ to 05-end-to-end/

* fix: update broken links in orchestrations README to match flat directory structure

python/samples/02-agents/tools/function_tool_declaration_only.py

@@ -0,0 +1,76 @@
+# Copyright (c) Microsoft. All rights reserved.
+
+import asyncio
+
+from agent_framework import FunctionTool
+from agent_framework.openai import OpenAIResponsesClient
+
+"""
+Example of how to create a function that only consists of a declaration without an implementation.
+This is useful when you want the agent to use tools that are defined elsewhere or when you want
+to test the agent's ability to reason about tool usage without executing them.
+
+The only difference is that you provide a FunctionTool without a function.
+If you need a input_model, you can still provide that as well.
+"""
+
+
+async def main():
+    function_declaration = FunctionTool(
+        name="get_current_time",
+        description="Get the current time in ISO 8601 format.",
+    )
+
+    agent = OpenAIResponsesClient().as_agent(
+        name="DeclarationOnlyToolAgent",
+        instructions="You are a helpful agent that uses tools.",
+        tools=function_declaration,
+    )
+    query = "What is the current time?"
+    print(f"User: {query}")
+    result = await agent.run(query)
+    print(f"Result: {result.to_json(indent=2)}\n")
+
+
+"""
+Expected result:
+User: What is the current time?
+Result: {
+  "type": "agent_response",
+  "messages": [
+    {
+      "type": "chat_message",
+      "role": {
+        "type": "role",
+        "value": "assistant"
+      },
+      "contents": [
+        {
+          "type": "function_call",
+          "call_id": "call_0flN9rfGLK8LhORy4uMDiRSC",
+          "name": "get_current_time",
+          "arguments": "{}",
+          "fc_id": "fc_0fd5f269955c589f016904c46584348195b84a8736e61248de"
+        }
+      ],
+      "author_name": "DeclarationOnlyToolAgent",
+      "additional_properties": {}
+    }
+  ],
+  "response_id": "resp_0fd5f269955c589f016904c462d5cc819599d28384ba067edc",
+  "created_at": "2025-10-31T15:14:58.000000Z",
+  "usage_details": {
+    "type": "usage_details",
+    "input_token_count": 63,
+    "output_token_count": 145,
+    "total_token_count": 208,
+    "openai.reasoning_tokens": 128
+  },
+  "additional_properties": {}
+}
+"""
+
+
+if __name__ == "__main__":
+
+    asyncio.run(main())