feat(start-work): add worktree path detection

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

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

src/hooks/start-work/worktree-detector.ts

@@ -0,0 +1,14 @@
+import { execFileSync } from "node:child_process"
+
+export function detectWorktreePath(directory: string): string | null {
+  try {
+    return execFileSync("git", ["rev-parse", "--show-toplevel"], {
+      cwd: directory,
+      encoding: "utf-8",
+      timeout: 5000,
+      stdio: ["pipe", "pipe", "pipe"],
+    }).trim()
+  } catch {
+    return null
+  }
+}