fix(mcp): ASCII-safe help/docstring text across the mcp command

Replace em-dashes with hyphens in the mcp module docstring, Typer help,
--allow-mutating help, and serve console output; add an ASCII-safety note.
Completes the v0.71.28 MCP ASCII cleanup so 'soup mcp --help' also stays
cp1252-safe (companion to a108c81).

src/soup_cli/commands/mcp.py

@@ -1,9 +1,12 @@
-"""soup mcp — Model Context Protocol server (v0.71.28).
+"""soup mcp - Model Context Protocol server (v0.71.28).
 
 ``soup mcp serve`` exposes Soup's read-only commands (plus two plan-only
 mutating tools) to any MCP client (Claude Code / Cursor / Cline / Continue)
 over stdio. The heavy ``mcp`` SDK is behind the ``[mcp]`` extra and imported
 lazily, so this command errors friendly-ly when the extra is missing.
+
+All user-facing help text stays ASCII (Windows terminal / cp1252 safety;
+mirrors the ``test_help_output_is_ascii_safe`` guard).
 """
 
 from __future__ import annotations
@@ -12,7 +15,7 @@ import typer
 
 app = typer.Typer(
     no_args_is_help=True,
-    help="Model Context Protocol server — drive Soup from any MCP client.",
+    help="Model Context Protocol server - drive Soup from any MCP client.",
 )
 
 
@@ -23,7 +26,7 @@ def serve(
         "--allow-mutating",
         help=(
             "Enable the plan-only mutating tools (train_start / export). Even "
-            "when enabled they only render the command that would run — v1 "
+            "when enabled they only render the command that would run - v1 "
             "never executes training or export. Off by default: those tools "
             "refuse."
         ),
@@ -31,7 +34,7 @@ def serve(
 ) -> None:
     """Start the stdio MCP server (read-only tools by default).
 
-    stdout is the JSON-RPC channel — all human-facing output goes to stderr.
+    stdout is the JSON-RPC channel - all human-facing output goes to stderr.
     Wire it into a client, e.g. `.mcp.json`:
 
         {"mcpServers": {"soup": {"command": "soup", "args": ["mcp", "serve"]}}}
@@ -51,5 +54,7 @@ def serve(
         raise typer.Exit(1) from None
 
     mode = "mutating tools ENABLED (plan-only)" if allow_mutating else "read-only"
-    console.print(f"[dim]soup mcp serve — stdio transport — {mode}. Waiting for a client...[/]")
+    console.print(
+        f"[dim]soup mcp serve - stdio transport - {mode}. Waiting for a client...[/]"
+    )
     run_stdio_server(allow_mutating=allow_mutating)