feat(cli): add mcp subcommand for reliable MCP server invocation

Add `spm mcp` subcommand that starts the MCP server via stdio
transport. This allows `npx -y sysprom mcp` to work reliably,
since npx cannot resolve secondary binaries from a package.

Update marketplace MCP config to use the new subcommand.

Author: Mearman

.claude-plugin/marketplace.json

@@ -27,12 +27,7 @@
       "mcpServers": {
         "sysprom": {
           "command": "npx",
-          "args": [
-            "-y",
-            "--package",
-            "sysprom",
-            "sysprom-mcp"
-          ]
+          "args": ["-y", "sysprom", "mcp"]
         }
       },
       "strict": false

src/cli/program.ts

@@ -54,3 +54,10 @@ export const commands: CommandDef[] = [
 for (const cmd of commands) {
 	buildCommander(cmd, program);
 }
+
+program
+	.command("mcp")
+	.description("Start the SysProM MCP server (stdio transport)")
+	.action(async () => {
+		await import("../mcp/server.js");
+	});