Migrate evm transactions to Motoko Core

[skilesare]

Summary

• establish the attributed ICDevs evm-txs-core successor
• migrate all source and test imports from mo:base to mo:core
• replace append-only Base Buffers with a Core PureList-backed builder
• update to moc 1.8.2 and immutable dependency pins
• document provenance, installation, and release history

Verification

• mops test --reporter files: all 6 files passed in 527.28s
• mops bench --compare --replica pocket-ic: all 18 instruction rows improved
• serialization: 13.24% to 19.82% fewer instructions
• message hashing: 10.95% to 17.96% fewer instructions
• access-list encoding: 28.53% fewer instructions
• heap delta unchanged; typed decode GC increased about 19% to 21% and remains documented

Mops publication is intentionally left to the maintainer.