fix: support new Hyprland lua config parser

[LuukBlankenstijn]

As described in #12 the new Hyprland Lua config parser does not support the keyword monitor command anymore. This PR fixes this by first trying the old behavior of keyword monitor and if this fails, tries to use the new Lua api.

Closes #12.

[LuukBlankenstijn]

I have been using this fix locally for a while, but I saw someone made an issue for it so here a PR.

[MuNeNiCK]

Thanks for the fix. I added one follow-up commit with unit tests for the Hyprland Lua monitor fallback, including the generated headless-output rule, non-numeric scale handling, Lua string escaping, malformed rule rejection, and non-legacy parser error detection.

Verified the merge result locally with:

• cargo fmt --check
• cargo test hyprland
• cargo test
• cargo clippy --all-targets -- -D warnings

I will merge this once the GitHub check finishes.