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- One superseded minimal_sample.py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/04-hosting/durabletask/02_multi_agent/README.md

@@ -0,0 +1,80 @@
+# Multi-Agent
+
+This sample demonstrates how to host multiple AI agents with different tools in a single worker-client setup using the Durable Task Scheduler.
+
+## Key Concepts Demonstrated
+
+- Hosting multiple agents (WeatherAgent and MathAgent) in a single worker process.
+- Each agent with its own specialized tools and instructions.
+- Interacting with different agents using separate conversation threads.
+- Worker-client architecture for multi-agent systems.
+
+## Environment Setup
+
+See the [README.md](../README.md) file in the parent directory for more information on how to configure the environment, including how to install and run common sample dependencies.
+
+## Running the Sample
+
+With the environment setup, you can run the sample using the combined approach or separate worker and client processes:
+
+**Option 1: Combined (Recommended for Testing)**
+
+```bash
+cd samples/04-hosting/durabletask/02_multi_agent
+python sample.py
+```
+
+**Option 2: Separate Processes**
+
+Start the worker in one terminal:
+
+```bash
+python worker.py
+```
+
+In a new terminal, run the client:
+
+```bash
+python client.py
+```
+
+The client will interact with both agents:
+
+```
+Starting Durable Task Multi-Agent Client...
+Using taskhub: default
+Using endpoint: http://localhost:8080
+
+================================================================================
+Testing WeatherAgent
+================================================================================
+
+Created weather conversation thread: <guid>
+User: What is the weather in Seattle?
+
+🔧 [TOOL CALLED] get_weather(location=Seattle)
+✓ [TOOL RESULT] {'location': 'Seattle', 'temperature': 72, 'conditions': 'Sunny', 'humidity': 45}
+
+WeatherAgent: The current weather in Seattle is sunny with a temperature of 72°F and 45% humidity.
+
+================================================================================
+Testing MathAgent
+================================================================================
+
+Created math conversation thread: <guid>
+User: Calculate a 20% tip on a $50 bill
+
+🔧 [TOOL CALLED] calculate_tip(bill_amount=50.0, tip_percentage=20.0)
+✓ [TOOL RESULT] {'bill_amount': 50.0, 'tip_percentage': 20.0, 'tip_amount': 10.0, 'total': 60.0}
+
+MathAgent: For a $50 bill with a 20% tip, the tip amount is $10.00 and the total is $60.00.
+```
+
+## Viewing Agent State
+
+You can view the state of both agents in the Durable Task Scheduler dashboard:
+
+1. Open your browser and navigate to `http://localhost:8082`
+2. In the dashboard, you can view:
+   - The state of both WeatherAgent and MathAgent entities (dafx-WeatherAgent, dafx-MathAgent)
+   - Each agent's conversation state across multiple interactions