fix(session): remove incorrect worktree removal in ensure_session

When worktree exists but session is missing, ensure_session was
incorrectly removing the worktree before recreating. This caused
issues when cmd_continue called ensure_worktree first (creating the
worktree) then ensure_session (which wrongly removed it).

The fix removes the block that removes worktree when session is missing.
If worktree exists, just create the session without touching the worktree.

Fixes #229

skills/kugetsu/scripts/kugetsu-session.sh

@@ -386,12 +386,6 @@ ensure_session() {
         return 0
     fi
     
-    if $worktree_exists && ! $session_exists; then
-        log "warn" "ensure_session" "Worktree exists but session is missing. Removing worktree to recreate both..."
-        remove_worktree_for_issue "$issue_ref"
-        worktree_exists=false
-    fi
-    
     if ! $worktree_exists && $session_exists; then
         log "warn" "ensure_session" "Session exists but worktree is missing. Removing stale session..."
         rm -f "$session_path"