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>

.gitignore

@@ -6,3 +6,7 @@ browse/dist/
 *.log
 bun.lock
 *.bun-build
+.env
+.env.local
+.env.*
+!.env.example