Skill: Motoko mo:base → mo:core Migration

AI Quick Checklist (Do Not Skip)

1. Versions

• Ensure dfx 0.31+
• Confirm repo compiles before starting
• In mops.toml add core = "2.2.0"
• update moc in mops.toml to "1.3.0" in [toolchain] and [requirements] sections.
• if wasmtime is present in mops.toml, upgrade it to at least "42.0.1"
• Do NOT remove base dependency until Phase 5 is completed

2. dfx.json Flags (per canister)

• wasm_memory_persistence: keep