Install dependencies after creating worktree

Run pnpm install in the new worktree directory before initializing the
Paperclip instance so that node_modules are ready when the init step runs.

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

cli/src/commands/worktree.ts

@@ -753,6 +753,19 @@ export async function worktreeMakeCommand(nameArg: string, opts: WorktreeMakeOpt
     throw new Error(extractExecSyncErrorMessage(error) ?? String(error));
   }
 
+  const installSpinner = p.spinner();
+  installSpinner.start("Installing dependencies...");
+  try {
+    execFileSync("pnpm", ["install"], {
+      cwd: targetPath,
+      stdio: ["ignore", "pipe", "pipe"],
+    });
+    installSpinner.stop("Installed dependencies.");
+  } catch (error) {
+    installSpinner.stop(pc.yellow("Failed to install dependencies (continuing anyway)."));
+    p.log.warning(extractExecSyncErrorMessage(error) ?? String(error));
+  }
+
   const originalCwd = process.cwd();
   try {
     process.chdir(targetPath);