[Build/CI] Split validation commands from mutating format and fix commands

[ashleyshaw]

Build/CI Summary

Ensure every validate:* command is read-only and move mutating behaviour to explicit format:* or fix:* commands.

Parent epic: #285.

Steps / Checklist

• Audit existing validation commands for file writes.
• Add or update read-only validation scripts.
• Add explicit write-capable formatter/fixer scripts.
• Update package scripts and documentation.
• PR uses correct branch prefix ci/ or build/.
• Approved by at least one maintainer.

Acceptance Criteria

• validate:* commands do not modify files.
• Write-capable commands are named format:* or fix:*.
• CI uses read-only validation commands.
• Documentation explains the distinction.

[linear-code]

LS-627