Fix default startup script (#929)

## What are the changes about?

Discussed in !920. Adds fixes to the startup script by removing the array usage (some shells use arrays different/unsupported) and adds stdout_behavior Inherit flag to the child process to propagate the echos to the TTY.

## What existing issue does this resolve?

N/A

## Pre-requisites

- [x] I have tested & confirmed the changes work locally

Reviewed-on: https://codeberg.org/fairyglade/ly/pulls/929
Reviewed-by: AnErrupTion <anerruption@disroot.org>
Co-authored-by: hynak <hynak@noreply.codeberg.org>
Co-committed-by: hynak <hynak@noreply.codeberg.org>

src/main.zig

@@ -312,7 +312,7 @@ pub fn main() !void {
 
     if (state.config.start_cmd) |start_cmd| {
         var start = std.process.Child.init(&[_][]const u8{ "/bin/sh", "-c", start_cmd }, state.allocator);
-        start.stdout_behavior = .Ignore;
+        start.stdout_behavior = .Inherit;
         start.stderr_behavior = .Ignore;
 
         handle_start_cmd: {