Add `pigz`

[MeteorsLiu]

Use write-formula SKILL to add https://github.com/madler/pigz to llarhub

[MeteorsLiu]

/code

[fennoai]

Add pigz formula

• Gather context and understand the request
• Research pigz library and its build requirements
• Write the pigz .gox formula file
• Commit and push changes
• Create pull request

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Created PR #9: #9

Files added:

• madler/pigz/versions.json — module metadata
• madler/pigz/pigz_cmp.gox — semver version comparator (v2.x tag format)
• madler/pigz/v2.4/pigz_llar.gox — build formula

Build notes: pigz uses a plain Makefile with no install target. The formula builds with make pigz, injecting the zlib include/lib paths via CFLAGS/LIBS overrides, then manually installs the pigz and unpigz binaries to bin/.