Fix multiple issues found under Linux

[lhecker]

Fixed:

• sighandler_t warning in nightly
• cppdbg + gdb pretty printing
• UTF8 parsing for SGR mouse coords

[lhecker]

Compilation speed under Linux continues to make me happy, but at the same time, I genuinely don't understand how linuxbros bear with that poor debugger ecosystem. It's fast, but it's also unnecessarily fiddly. 🥲

[JaredTweed]

Hey, I am the guy who made PR #628 (single line Linux installer).

On Linux, my recommendation for the least-pain Rust setup is VS Code with Rust Analyzer + CodeLLDB. avoid cppdbg with LLDB, use rust-gdb if you need GDB, and run any mouse-heavy TUIs in an external terminal instead of RustRover’s.

Hope this helps!