Make workspace-core the default MCP profile

Flip bare pyro mcp serve, create_server(), and Pyro.create_server() to default to workspace-core in 4.0.0 while keeping workspace-full as the explicit advanced opt-in surface.

Rewrite the MCP-facing docs and host-specific examples around the bare default command, update package and catalog compatibility to 4.x, and move the public-contract wording from 3.x compatibility guidance to the new stable default.

Adjust the server, API, and contract tests so bare server creation now asserts the workspace-core tool set, while explicit workspace-full coverage continues to prove shells, services, snapshots, and disk tools remain available.

Validation: uv lock; .venv/bin/pytest --no-cov tests/test_cli.py tests/test_api.py tests/test_server.py tests/test_public_contract.py; UV_CACHE_DIR=.uv-cache make check; UV_CACHE_DIR=.uv-cache make dist-check; real guest-backed smoke for bare Pyro.create_server() plus explicit profile="workspace-full".

examples/openai_responses_workspace_core.py

@@ -4,10 +4,10 @@ Requirements:
 - `pip install openai` or `uv add openai`
 - `OPENAI_API_KEY`
 
-This is the recommended persistent-chat example. It mirrors the
-`workspace-core` MCP profile by deriving tool schemas from
-`Pyro.create_server(profile="workspace-core")` and dispatching tool calls back
-through that same profiled server.
+This is the recommended persistent-chat example. In 4.x the default MCP server
+profile is already `workspace-core`, so it derives tool schemas from
+`Pyro.create_server()` and dispatches tool calls back through that same
+default-profile server.
 """
 
 from __future__ import annotations
@@ -45,7 +45,7 @@ async def run_openai_workspace_core_example(*, prompt: str, model: str = DEFAULT
     from openai import OpenAI  # type: ignore[import-not-found]
 
     pyro = Pyro()
-    server = pyro.create_server(profile="workspace-core")
+    server = pyro.create_server()
     tools = [_tool_to_openai(tool) for tool in await server.list_tools()]
     client = OpenAI()
     input_items: list[dict[str, Any]] = [{"role": "user", "content": prompt}]