fix(kugetsu): fix worktree name dash inconsistency and add worktree tests

- Fix issue_ref_to_worktree_name: use single dash for # like filename does
- Add tests for: pm-agent in index, destroy --pm-agent, worktree_path in session
- Add tests for: prune detects/removes orphaned worktrees, destroy removes worktree
- Add tests for: session file v2.2 format with worktree_path

All 28 tests pass.

skills/kugetsu/scripts/kugetsu

@@ -61,7 +61,7 @@ ensure_worktree_dir() {
 
 issue_ref_to_worktree_name() {
     local issue_ref="$1"
-    echo "$issue_ref" | sed 's/[\/:]/-/g' | sed 's/#/--/'
+    echo "$issue_ref" | sed 's/[\/:]/-/g' | sed 's/#/-/'
 }
 
 issue_ref_to_worktree_path() {