Remove stale TODO masking Bun import-attributes loader matrix

Follow up #137 by removing the remaining native TODO rewrite for the byte-identical Bun js/bun/import-attributes/import-attributes.test.ts corpus.

Evidence:

• Home corpus copy matches Bun upstream byte-for-byte
• full-VM routing already exists
• the unmodified upstream file passes in Home: 12 pass, 0 fail, 8 snapshots, 91 assertions
• the normal checked-in corpus path is still masked as one TODO solely because rewriteBunTestImport retains a stale rewriteNativeTodoCorpus branch

Acceptance:

• remove the stale rewrite without modifying the upstream corpus
• exact checked-in path reports 12 pass / 0 fail / 91 assertions
• debug and full home_test gates pass
• commit/push directly to main as Chris Breuer and update #66

Completed in 327a951.

Removed the stale TODO rewrite left after #137. The byte-identical upstream corpus now executes on its normal checked-in path through the already-established full-VM route.

Acceptance evidence:

• exact import-attributes.test.ts: 12 pass, 0 fail, 8 snapshots, 91 assertions
• covers JS, TS, JSON, JSONC, TOML, YAML, text, sqlite, and file loader behavior across static import, dynamic import, require, and Bun.build paths
• zig build debug --summary failures: pass
• zig build test -Dfilter=home_test --summary failures: pass

The broader Bun parity goal continues in #66.