GateFlow v2.5.3

Command-first local CLI release.\n\n- Adds tools/gateflow_cli.py with status, tui, agents list, agents create, and shell commands.\n- Adds real local agent creation that writes Claude-compatible files under plugins/gateflow/agents/.\n- Adds TUI shortcut a for creating agents from the dashboard.\n- Improves terminal colors with semantic status, heading, selection, footer, and muted styles.\n- Updates docs, release metadata, and tests.\n\nVerification: python3 -m unittest; python3 tools/validate_gateflow.py --version 2.5.3; CLI status/list/shell/create smoke; TUI snapshot and PTY launch/quit smoke.