fix(cli): replace panicking unwrap/index with proper error propagation in linker

[junovhs]

run_link_inner could have a panic in two ways when fixing the output path -

• .unwrap() on .position() when searching for -o in linker args, it panics if -o is absent
• Direct index access args[out + 1] , it panics if -o is the last argument with nothing after it
• .unwrap() on .find() for /OUT: on Windows. same issue.

I also was inclined to replace .expect("Failed to run linker") on cmd.output() with .context(...)? so that the linker spawn failures propagate clean.

extracted the output path resolution into resolve_output_path for clarity. Errors now propagate via anyhow::Context instead of paniking.