docs(python-mcp): update skill, instructions, agent, and plugin for MCP Python SDK v2 🤖🤖🤖 (#4737)

* docs(python-mcp-server-generator): rewrite skill for MCP Python SDK v2

- Target MCP Python SDK v2 (MCPServer) and MCP specification 2026-07-28
- Replace FastMCP imports with `from mcp.server import MCPServer`
- Rewrite the description with explicit triggers and exclusions
- Add the compatibility field (uv, Python 3.10+, npx for the Inspector)
- Add a five-step workflow checklist: create, write, test, validate, configure
- Pin the SDK with `uv add "mcp[cli]>=2,<3"` and use a flat uv app layout
- Add server and in-memory Client test templates
- Add a test-fix-retest validation loop with `uv run pytest`
- Add a Gotchas section for SDK v1 to v2 changes and deprecated features
- Move Streamable HTTP guidance to references/streamable-http.md
- Remove generic guidance that the model already knows

* docs(python-mcp-server): update instructions for MCP Python SDK v2

- Target MCP Python SDK v2 (MCPServer) and MCP specification 2026-07-28
- Replace FastMCP imports with MCPServer and mcp.server.mcpserver imports
- Move transport options from the constructor to run() and streamable_http_app()
- Use Resolve and Elicit for user input instead of ctx.elicit()
- Use ctx.notify_tools_changed() for list change notifications
- Explain ToolError and MCPError behavior for tool failures
- Mark sampling, protocol logging, and roots as deprecated
- Add transport security, CORS, and multi-worker guidance
- Add an in-memory Client test pattern
- Rewrite the text in ASD-STE100 Simplified Technical English
- Use single-quoted frontmatter values

* docs(python-mcp-expert): update agent for MCP Python SDK v2

- Target MCP Python SDK v2 (MCPServer) and MCP specification 2026-07-28
- Replace the retired GPT-4.1 model with GPT-6 Sol
- Replace FastMCP guidance with MCPServer guidance
- Add guidance for transport options, Resolve and Elicit, and notify_tools_changed()
- Explain ToolError and MCPError behavior for tool failures
- Mark sampling, protocol logging, and roots as deprecated
- Add SDK v1 to v2 migration as a supported scenario
- Rewrite the text in ASD-STE100 Simplified Technical English
- Use single-quoted frontmatter values

* chore(python-mcp-development): update plugin metadata for MCP Python SDK v2

- Remove FastMCP from the plugin description and README
- Describe the actual plugin contents: one skill and one agent
- Replace the fastmcp keyword with mcp-python-sdk
- Bump the plugin version to 2.0.0
- Regenerate marketplace.json and docs/README.plugins.md

* fix(python-mcp-server-generator): correct transport security, lifespan, and SSE notes

* fix(python-mcp-server): remove invalid structured_output advice and align with skill

* fix(python-mcp-expert): add missing SDK v2 rules and remove repeated guidance

* fix(python-mcp-expert): remove the retired model from frontmatter

* fix(python-mcp-server-generator): state Node.js as the MCP Inspector prerequisite

skills/python-mcp-server-generator/references/streamable-http.md

@@ -0,0 +1,46 @@
+# Streamable HTTP Servers
+
+Use this transport only for a remote server. A local server uses stdio.
+
+## Run the server
+
+Replace `mcp.run()` in `server.py`:
+
+```python
+import os
+
+if __name__ == "__main__":
+    mcp.run(
+        transport="streamable-http",
+        host=os.environ.get("HOST", "127.0.0.1"),
+        port=int(os.environ.get("PORT", "8000")),
+    )
+```
+
+Clients connect to `http://HOST:PORT/mcp`. For VS Code, write `.vscode/mcp.json`:
+
+```json
+{
+  "servers": {
+    "demo": {
+      "type": "http",
+      "url": "http://localhost:8000/mcp"
+    }
+  }
+}
+```
+
+## Mount the server in an ASGI app
+
+1. Use `mcp.streamable_http_app()` to mount the server in a Starlette or FastAPI app.
+2. Give the transport options to `streamable_http_app()`. This method has no `port` option.
+3. Make the lifespan of the host app enter `mcp.session_manager.run()`.
+
+## Gotchas
+
+- Requests on the 2026-07-28 revision have no session. Any replica can answer a request.
+- `stateless_http=True` changes only how the server serves clients of earlier revisions.
+- `json_response=True` sends one JSON body for each request. In this mode, the server cannot send progress notifications during the request.
+- If you do not set `transport_security`, the SDK checks the `Host` and `Origin` headers only when the host is `127.0.0.1`, `localhost`, or `::1`. For all other hosts, for example `0.0.0.0` or a public host name, the server does no check. For these hosts, give `transport_security=TransportSecuritySettings(allowed_hosts=[...], allowed_origins=[...])` (from `mcp.server.transport_security`) to `run()` or `streamable_http_app()`.
+- For browser clients, add CORS to the host app. Allow the `Mcp-*` request headers. Expose the `Mcp-Session-Id` response header.
+- For more than one worker, set `request_state_security=RequestStateSecurity(keys=[...])` (from `mcp.server.mcpserver`) on `MCPServer`. Use the same keys and the same server name on all workers.