Add uvx support

Add uvx as a supported package manager so that `uvx` commands are
routed through safe-chain's MITM proxy for malware detection, just
like `uv`. Previously, `uvx` bypassed all safe-chain protections.

The uvx package manager reuses the existing uv command runner since
uvx is functionally equivalent to `uv tool run`.

Fixes #268

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

packages/safe-chain/bin/aikido-uvx.js

@@ -0,0 +1,16 @@
+#!/usr/bin/env node
+
+import { main } from "../src/main.js";
+import { initializePackageManager } from "../src/packagemanager/currentPackageManager.js";
+import { setEcoSystem, ECOSYSTEM_PY } from "../src/config/settings.js";
+
+// Set eco system
+setEcoSystem(ECOSYSTEM_PY);
+
+initializePackageManager("uvx");
+
+(async () => {
+  // Pass through only user-supplied uvx args
+  var exitCode = await main(process.argv.slice(2));
+  process.exit(exitCode);
+})();