fix: file creation when directory already exists (#8892)

Resolves #8890 

If you try to create the config file when the directory already exists,
you (I) get an error that the _file_ path already exists.
```
warning(config): error creating template config file err=error.PathAlreadyExists
```
Even though the file does not exist. By changing the API entry point,
this error goes away.

I have no solid explanation for why this change works.


| State | Old Behavior | New Behavior |
|--------|--------|--------|
| A config file exists | N/A | N/A |
| No config file, no directory | create directory and config file | N/A
|
| No config file, yes directory | fail to create on config file | create
config file |

This behavior is confirmed on my macOS 26 machine. It is the least
intrusive change I could make, and in all other situations should be a
no-op.

src/config/Config.zig

@@ -3357,7 +3357,7 @@ pub fn loadOptionalFile(
 fn writeConfigTemplate(path: []const u8) !void {
     log.info("creating template config file: path={s}", .{path});
     if (std.fs.path.dirname(path)) |dir_path| {
-        try std.fs.makeDirAbsolute(dir_path);
+        try std.fs.cwd().makePath(dir_path);
     }
     const file = try std.fs.createFileAbsolute(path, .{});
     defer file.close();