Document temporary wikibrowser ABI split

[humandebri]

Summary

• Document why wikibrowser temporarily follows the production VFS ABI instead of the checked-in canister DID.
• Mark local Internet Identity e2e as out of scope while the production and repository ABIs are split.
• Add checks that keep the temporary ABI split explanation and post-review reintegration notes in place.

Validation

• pnpm --dir wikibrowser test
• pnpm --dir wikibrowser lint
• pnpm --dir wikibrowser typecheck
• pnpm --dir wikibrowser build
• Production list_databases decode against xis3j-paaaa-aaaai-axumq-cai