fix(zip): use zipinfo to preflight zip extraction on unix

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

src/shared/zip-entry-listing/read-zip-symlink-target.ts

@@ -0,0 +1,23 @@
+import { spawn } from "bun"
+
+export async function readZipSymlinkTarget(
+	archivePath: string,
+	entryPath: string
+): Promise<string | undefined> {
+	const proc = spawn(["unzip", "-p", archivePath, "--", entryPath], {
+		stdout: "pipe",
+		stderr: "pipe",
+	})
+
+	const [exitCode, stdout, stderr] = await Promise.all([
+		proc.exited,
+		new Response(proc.stdout).text(),
+		new Response(proc.stderr).text(),
+	])
+
+	if (exitCode !== 0) {
+		throw new Error(`zip symlink target read failed (exit ${exitCode}): ${stderr}`)
+	}
+
+	return stdout || undefined
+}