Refactor CLI command modules for exploration

[rosterloh]

Summary

• Split all CLI command handlers into focused command modules: topics, nodes, echo, and parameters.
• Keep talos-cli/src/main.rs as the composition root for arg parsing, client setup, and dispatch.
• Split parameter protocol types and TUI parameter input handling into focused modules.
• Make list-topics and list-nodes propagate agent error responses instead of printing and exiting successfully.

Verification

• rtk cargo fmt -- --check
• rtk cargo check -p talos-common -p talos-cli -p talos-tui --offline
• rtk cargo test -p talos-common --offline
• rtk cargo test -p talos-cli --offline
• rtk cargo test -p talos-tui --offline
• with rclrs_ws/install/setup.zsh sourced: rtk cargo check --workspace --offline
• with rclrs_ws/install/setup.zsh sourced: rtk cargo test --workspace --offline