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- One superseded minimal_sample.py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/orchestrations/sequential_agents.py

@@ -0,0 +1,79 @@
+# Copyright (c) Microsoft. All rights reserved.
+
+import asyncio
+from typing import cast
+
+from agent_framework import Message
+from agent_framework.azure import AzureOpenAIChatClient
+from agent_framework.orchestrations import SequentialBuilder
+from azure.identity import AzureCliCredential
+
+"""
+Sample: Sequential workflow (agent-focused API) with shared conversation context
+
+Build a high-level sequential workflow using SequentialBuilder and two domain agents.
+The shared conversation (list[Message]) flows through each participant. Each agent
+appends its assistant message to the context. The workflow outputs the final conversation
+list when complete.
+
+Note on internal adapters:
+- Sequential orchestration includes small adapter nodes for input normalization
+  ("input-conversation"), agent-response conversion ("to-conversation:<participant>"),
+  and completion ("complete"). These may appear as ExecutorInvoke/Completed events in
+  the stream—similar to how concurrent orchestration includes a dispatcher/aggregator.
+  You can safely ignore them when focusing on agent progress.
+
+Prerequisites:
+- Azure OpenAI access configured for AzureOpenAIChatClient (use az login + env vars)
+"""
+
+
+async def main() -> None:
+    # 1) Create agents
+    client = AzureOpenAIChatClient(credential=AzureCliCredential())
+
+    writer = client.as_agent(
+        instructions=("You are a concise copywriter. Provide a single, punchy marketing sentence based on the prompt."),
+        name="writer",
+    )
+
+    reviewer = client.as_agent(
+        instructions=("You are a thoughtful reviewer. Give brief feedback on the previous assistant message."),
+        name="reviewer",
+    )
+
+    # 2) Build sequential workflow: writer -> reviewer
+    workflow = SequentialBuilder(participants=[writer, reviewer]).build()
+
+    # 3) Run and collect outputs
+    outputs: list[list[Message]] = []
+    async for event in workflow.run("Write a tagline for a budget-friendly eBike.", stream=True):
+        if event.type == "output":
+            outputs.append(cast(list[Message], event.data))
+
+    if outputs:
+        print("===== Final Conversation =====")
+        for i, msg in enumerate(outputs[-1], start=1):
+            name = msg.author_name or ("assistant" if msg.role == "assistant" else "user")
+            print(f"{'-' * 60}\n{i:02d} [{name}]\n{msg.text}")
+
+    """
+    Sample Output:
+
+    ===== Final Conversation =====
+    ------------------------------------------------------------
+    01 [user]
+    Write a tagline for a budget-friendly eBike.
+    ------------------------------------------------------------
+    02 [writer]
+    Ride farther, spend less—your affordable eBike adventure starts here.
+    ------------------------------------------------------------
+    03 [reviewer]
+    This tagline clearly communicates affordability and the benefit of extended travel, making it
+    appealing to budget-conscious consumers. It has a friendly and motivating tone, though it could
+    be slightly shorter for more punch. Overall, a strong and effective suggestion!
+    """
+
+
+if __name__ == "__main__":
+    asyncio.run(main())