A tools bundle speaks MCP over stdio: the loop in TypeScript, and skeleton SDKs for Python, Go, Rust and C (hq ADR 0187)

The node's runtime launches a tools bundle as a process and speaks MCP over stdio to it, so a tool
may be written in any language and the transport stays in the runtime (ADR 0039's refusal, kept).
Each SDK is the loop and the tool type and nothing else: `@novox/mesh-sdk/stdio` (serveStdio, and
serveRegisteredOverStdio for a bundle that already registers the in-process way), python/, go/,
rust/ and c/ beside it, each with an example answering `greet` and the seat verb `node-lamp.on`.
Skeletons, by the operator's direction: the bare minimum one bundle per language needs to be built
and answer, proven here by each example answering tools/list and tools/call on stdio.

python/example.py

@@ -0,0 +1,13 @@
+#!/usr/bin/env python3
+# A tools bundle in Python: one tool of its own and one seat verb, served over stdio.
+import os
+import sys
+
+sys.path.insert(0, os.path.dirname(os.path.abspath(__file__)))
+from mesh_sdk import Tool, serve  # noqa: E402
+
+serve("python-example", [
+    Tool("greet", "say hello", lambda a: {"greeting": f"hello {a.get('who', 'world')}", "language": "python"},
+         {"who": {"type": "string", "description": "whom"}}),
+    Tool("node-lamp.on", "the seat's verb", lambda a: {"on": True, "language": "python"}),
+])