Fix task OMP terminal colors and Unicode rendering #41

Pin omp-manager 0ae6734. Detached task tmux sessions now launch with an explicit tmux-256color terminal, RGB capability overrides, truecolor environment and C.UTF-8 locale. The existing OMP theme and picker layout are unchanged. 13 manager tests, the Nix task-image-context build, and real OMP rich-render/keyboard/RPC/session-resume tests pass (mock provider). Full homura toplevel evaluation passes with a temporary Orpheus input override. Rebuild homura after merge; re-create task containers to pick up the new image. No homura activation performed.