vuru Odin 2026.05 update

Updated vuru from Odin 2026.01 APIs to 2026.05.

I am writing down the API changes here so I do not have to find them again next time.

• Replaced make([]dynamic) with [dynamic; N] inline array declarations.
• Updated os.read_entire_file / os.write_entire_file call sites to use nil error checks.
• Replaced recursive os.make_directory logic with os.make_directory_all.
• Replaced fi.is_dir checks with fi.type == .Directory.
• Updated os.open usage for (handle, err) return signature.
• Removed unused core:io, core:os imports and the old parent_dir helper.
• Added vuru src install subcommand using host_install_pkg.

musl support is still missing. vuru is written in Odin, and I currently maintain the Odin template in VUP.

Cross-compiling vuru should be manageable. Odin is the unknown: its template needs musl support, and compiler or toolchain assumptions may need upstream fixes.

I want musl users to install vuru instead of adding every repository category by hand from the website.