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/checks/port-check.ts

@@ -0,0 +1,24 @@
+import type { PaperclipConfig } from "../config/schema.js";
+import { checkPort } from "../utils/net.js";
+import type { CheckResult } from "./index.js";
+
+export async function portCheck(config: PaperclipConfig): Promise<CheckResult> {
+  const port = config.server.port;
+  const result = await checkPort(port);
+
+  if (result.available) {
+    return {
+      name: "Server port",
+      status: "pass",
+      message: `Port ${port} is available`,
+    };
+  }
+
+  return {
+    name: "Server port",
+    status: "warn",
+    message: result.error ?? `Port ${port} is not available`,
+    canRepair: false,
+    repairHint: `Check what's using port ${port} with: lsof -i :${port}`,
+  };
+}