Version drift: moc toolchain pinned at 1.6.0 / 1.7.0 / 1.8.1 / 1.9.0 across skills

[raymondk]

The [toolchain] moc pin diverges four ways:

• skills/internet-identity/SKILL.md:274 — moc = "1.6.0"
• skills/mops-cli/SKILL.md:28 — moc = "1.7.0"
• skills/caffeine-app/SKILL.md:214 — moc = "1.8.1"
• skills/icp-cli/SKILL.md:34,389 — moc = "1.9.0"

Some divergence may be intentional (Caffeine pins its own toolchain), but the general-purpose skills should agree on a current version.