chore: migrate build tooling from dfx to icp-cli

[marc0olo]

Summary

• Migrate build tooling from dfx to icp-cli, @icp-sdk/bindgen, and mops
• Upgrade all Motoko canisters from mo:base to mo:core@2.0.0 with moc@1.2.0
• Simplify superheroes superpowers type from linked list to vec text
• Add Mops and Cargo caching to CI for faster builds

Changes

Build system:

• Replace dfx.json with icp.yaml (10 canisters: 7 Motoko, 3 Rust)
• Add mops.toml for Motoko toolchain and package management
• Use @icp-sdk/bindgen (icp-bindgen) for TypeScript declaration generation
• Hand-write .did files for all Motoko canisters (previously auto-generated by dfx)
• Pin Rust recipe to dfinity/icp-cli-recipes@e083017 (fixes gzip compression on Linux)

Motoko upgrades:

• All imports changed from mo:base/* to mo:core/*
• phonebook.mo: HashMap → Map
• superheroes.mo: List.List<Text> → [Text], Trie → Map
• Add interfaces/ modules for inter-canister calls in the multicanister example

CI (e2e-test-nodejs.yml):

• Replace dfinity/setup-dfx with icp-cli + ic-wasm + ic-mops
• Use mops install to pre-cache the Motoko compiler before parallel builds
• Add actions/cache for Mops (toolchain + packages) and Cargo (registry + build artifacts)

Cleanup:

• Delete dfx.json and dfx-generated actor wrappers (declarations/index.{js,d.ts})
• Remove /.dfx/ from .gitignore, add /.icp/cache/ and /.mops/