Add CLI package, config file support, and workspace setup

Add cli/ package with initial scaffolding. Add config-schema to shared
package for typed configuration. Add server config-file loader for
paperclip.config.ts support. Register cli in pnpm workspace. Add
.paperclip/ and .pnpm-store/ to gitignore. Minor Companies page fix.

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

cli/src/utils/net.ts

@@ -0,0 +1,18 @@
+import net from "node:net";
+
+export function checkPort(port: number): Promise<{ available: boolean; error?: string }> {
+  return new Promise((resolve) => {
+    const server = net.createServer();
+    server.once("error", (err: NodeJS.ErrnoException) => {
+      if (err.code === "EADDRINUSE") {
+        resolve({ available: false, error: `Port ${port} is already in use` });
+      } else {
+        resolve({ available: false, error: err.message });
+      }
+    });
+    server.once("listening", () => {
+      server.close(() => resolve({ available: true }));
+    });
+    server.listen(port, "127.0.0.1");
+  });
+}