fix(integrations): use npx directly instead of sh -c wrapper (#61)

The librefang MCP security check blocks shell interpreters (sh, bash)
as commands. Use `command = "npx"` with `$HOME` in args — the runtime
now expands env vars in args natively.

integrations/filesystem.toml

@@ -7,11 +7,8 @@ tags = ["files", "local", "read", "write", "search"]
 
 [transport]
 type = "stdio"
-command = "sh"
-args = [
-  "-c",
-  "exec npx -y @modelcontextprotocol/server-filesystem@latest \"$HOME\"",
-]
+command = "npx"
+args = ["-y", "@modelcontextprotocol/server-filesystem@latest", "$HOME"]
 
 [health_check]
 interval_secs = 60