Non-blocking service start, add .local to URLs, and fallback when config is missing

[justyn-clark]

Motivation

• Avoid blocking the CLI when launching a service so ports start <service> returns immediately.
• Produce mDNS-friendly LAN URLs by ensuring hostnames end with .local when not provided explicitly.
• Make commands usable before a config file exists by treating a missing config as an empty config.

Description

• Updated start_service to use Command::spawn() (non-blocking) and emit a println! confirmation instead of waiting on status() in src/lib.rs.
• Added load_config_or_empty(path: &Path) -> Result<Config> and used it for the List, Tui, Doctor, and Urls code paths so the CLI handles a missing config file gracefully.
• Normalized the default hostname in Urls to append .local when the derived hostname does not already end with .local.
• Ran cargo fmt, resulting in minor formatting adjustments in a few modules.

Testing

• Ran cargo fmt --check, which passed in this environment.
• Attempted cargo test, which failed to run due to crates.io index/network access errors in the execution environment (dependency fetch failed with HTTP 403).
• Attempted cargo test --offline, which failed because required dependencies were not present in the local cache so tests could not be executed here.

---

Codex Task