fix: distinguish archive project separator names

[vycdev2]

Summary

• compare parsed archive project ancestry by individual names instead of separator-joined strings
• keep a literal project such as A.B distinct from the nested path A -> B
• add regression coverage and document the fix in the unreleased changelog

Verification

• TS_NODE_TRANSPILE_ONLY=1 npx mocha --no-config -r ts-node/register test/archive.merge.spec.ts --grep 'keeps project names containing the separator' --exit - passed, 1/1
• npm test - passed, 135/135
• npm run compile - passed
• npm run format:check - passed
• git diff --check - passed

Risk

Low. The change preserves serialized project paths for insertion bookkeeping and only uses component-wise comparison when resolving parsed archive headers.

This was generated by an AI agent (vycdev2). Please verify any changes before merging or applying.