feat: conductor.json lifecycle hooks + .env propagation across worktrees

bin/dev-setup now copies .env from main worktree so API keys carry
over to Conductor workspaces automatically. conductor.json wires up
setup and archive hooks.

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

conductor.json

@@ -0,0 +1,6 @@
+{
+  "scripts": {
+    "setup": "bin/dev-setup",
+    "archive": "bin/dev-teardown"
+  }
+}